I waited a day to reply to this post to digest the post and to see what other advice you would get.
I think you will notice two distinct viewpoints on this issue and if you pay attention to who is offering the advice you will understand why those viewpoints differ. Newer runners will take the "great, you can do it!" attitude. More seasoned runners will take the more cautious attitude. We have the experience to know that this is not a joke and you are setting yourself up for injury and failure. Even if you somehow make it across all four finish lines in January, at what cost will it be? Distance running requires hours of training that you have never had to carve out of your life. Do you know how long a 20 mile long run takes? Do you realize that you will have one Christmas weekend? For two months you will need to carve out 3-5 hours to run. Every weekend. Then there is the physical aspect. You say you are in good shape, have you ever worked out for 2 hours straight? 3 hours? 4 hours? 5 days a week? For a year, continuously? You are getting ready to ask a lot of your body. Running for 40 minutes at a time is no comparison to running for even 90 minutes at a time and then getting up the next day and doing it again. Working out for an hour with weights is not the same as running non-stop for an hour. You will hurt in places that you didn't know you had, and it will be awesome, but it is a huge adjustment and can be mentally draining in addition to physically exhausting.
Reading your posts, you clearly have not thought this through as you have no clear training plan, you didn't even think to set up practice races prior to the races and are going to wait for an online training plan. This is because you have no experience and have no idea what you are doing. I know I am being harsh, but the fact is, somebody needs to be because you have just sunk over $1000 between you and your wife into a race that you are completely unprepared to run. I also find it interesting that you say you can't afford a trainer, yet you just signed up for the most expensive race in the country.
If you really want to be prepared you need to start training now and that includes going to your local running store, buying an appropriate pair of running shoes that have been fit to your gait (not big box store) and then joining your local running club and finding a coach. You need a training plan that is personalized to you and I strongly advise against waiting for Galloway (or any other online program) for a few reasons.
1. Online programs are not going to be able to evaluate your specific needs
2. For the Dopey specifically, Galloway will assume you are a seasoned runner and start the plan where you are not ready.
3. Galloway does not actually approve of even the Goofy, I can't imagine the head explosion he is having over this race challenge. If you choose to do one of his other programs you will not do better, as he doesn't like to have you run more than 2 days in a row (you definitely need to practice running multiple days in a row at least a few weeks this year)
4. If/when you have injuries, you need a local in-person coach who can help you get through the issues.
5. A local coach can set up long run routes for you and your wife and be a motivation for you that an online program cannot provide. Since you don't know how you will react to the new demands to your time, being held accountable will help keep you on track and keep your training on schedule. This will also help keep you injury-free and keep you from over-training.
After finding a local running coach, you need to sit down with them and find at least: a local 5K as soon as possible, a 10K in the summer/early fall and 1/2 marathon in the fall (preferably in the beginning of October) that you can run as training races. If you can find another 10 miler-1/2 in late November to December that would be helpful too. These will help you learn about getting up early, fueling on the run, grabbing cups in water stops, dealing with race morning jitters, porta-potty lines, what you need in your bag, etc. Local races usually are fairly inexpensive and can be really fun (and are really what you should have focused on first, but I will let that go now
). I would try to race these runs with the exception of the last one, you will have plenty of time to recover from an October race and your risk of injury is already bad, a race isn't really going to be that big a deal if you are training properly at that point.
And FWIW:
1. They do sweep.
2. It is timed, and you are supposed to finish in the allotted time for each race. If you don't, please be man enough to own up to that and not accept a medal you did not earn. That is a pet peeve of mine with the Goofy runners in the past. You paid for the opportunity to attempt the Dopey, not the guarantee of the medal.
3. You are allowed to bow out gracefully and we will as true runners respect you and your decision because we all have had a bad race and we all have had a race when we made a bad decision but in the long run we all want to be able to race another day. We are out there for the love of running and at least for me, the biggest frustration is when someone is ill prepared for a race and then "hates" running because of it (kind of like the Disney haters who show up to the parks with no plan and are surprised that they have to wait in line and can't eat in the Castle
). There is a saying in ultarunning "DNF = Did Nothing Fatal"
)
I ended up doing that (against similar advice as I'm offering) and got a terrible case of shin splints that took me weeks to rehab. Slow and steady in building up your mileage is the key. 
