I agree, there are no RV's out there that can safely transport 13 people. No way, no how. And in some states you could actually get ticketed for it.
That said, RV's don't exactly fly down the highway. They get between 7-10 mpg, so my guess is taht anything you save in airfare will be more than eaten up by RV rental fees, insurance (yes, unlike rental cars it's mandatory to take the insurance on the RV) and fuel. If you are travelling on any toll roads the tolls will be higher than a regular car.
Now, as far as time, I figure it would take at least 30 hours from NJ to Orlando in an RV. Like I said, you can't go fast in them. Even with delays, unless weather is involved, in which case you will likely also be delayed in driving, it does'nt take that long to fly.
But I guess it's all moot anyhow, because you can't put 13 in an RV.
If you are that desperate, get hold of one of the Stage Coach companies and check on the rates for a weekly rental with driver, you would get a luxury coach with 12 bunks and a rear lounge which would sleep two. Video games, satllite tv, great stereo systems, etc.
try:
http://www.coasttocoastcoach.com/main.htm
www.floridacoach.com
http://www.staleycustomcoach.com/ROYALVIP.htm
http://www.netwide.net/FCC/
Depending on the time of year, they *can* be somewhat negotiable, but it's not gonna be cheap.
Personally, I'd just stick with the current plan and fly.
Anne