I see your concerns with these locations and will try to state what I know of each one.
1. The YCG is a beautiful place. I would not worry about the building being in most of your shots. You could tell that concern to your photographer, but I certainly don't think have parts of the building in your pictures will take away from the beauty of the location.
2. I don't know a whole lot about Sunset Point, so I will leave that one alone, but I don't think that is traditionally a location for custom weddings. But hey, At Disney anything is Possible.
3. Sea Breeze Point.... I can't say enough about see Breeze Point as I think it is such a beautiful location! This was where we were going to have our ceremony before we switched to the Wedding Pavilion. Ther is MORE than enough room for 45 guests in the pavilion/Gazebo at SBP.. They will set the chairs up on both sides of the arch way so you have a small isle in between. you would actually walk down one of the wings, unless you would like to walk down the shorter isle in between your guests. (Which has been done). What I like about the SBP is you can keep it as simple or as eleborate as you want with decor and both look beautiful! I would not worry one bit about privacy. Disney will have people standing watch so no one will intrude on your ceremony. You are far enough away on the path that you shouldn't be bothered by the passerby's walking to Epcot. And I certainly don't think you will be bothered by the noise at ESPN. When you are all dressed up in your wedding cloths, you might find that you actually like the attention of people watching you and wishing you congrats. Having people "spy" on us was not such a big deal to me when we were going to have our ceremony there. I figured the more people who want to witness the better. Besides, getting a glimpse of an actual wedding take place at WDW may be the highlight of someones vacation! If you do like SBP but are still stuck on the privacy issue, here where you can add more decore. You can have tull curtains of some sort around the gazebo, (although IMO it takes away from the natural beauty of SBP). One thing I will caution you on is if you have a unity candle at SBP it will not stay lit. Also, there may be some noise from passing boats and such. Although I have heard couples say that they liked it when boats would go by and honk there horn for them to wish them luck!
4. Although the Sunset terrace at the Wildreness lodge is lovely and private, it will not accomodate a group size of 45.
Are you set against having a Wedding Pavilion Wedding?
Have you looked into any of the locations at Epcot?
I know that you did a site visit, but if you need any pics of any location let me know and I will try to dig one up for you.
Hope all that help!