I had pretty much the same requirements you have when we were looking. We just replaced a 2009 Keystone Fusion 302 (that was totaled) with a 2015 Keystone Impact 311. Both will meet most of your needs. Both are 35 feet with a dedicated garage. Both have two slides (living and bedroom). Both have 10 foot garages so you couldn't fit a 4 seat RZR in it. I did find however that by adding two tie down anchors at the rear corners of the beaver tail, you could extend your "usable" garage space by another 1.5 - 2 feet.
Fusion doesn't make the 302 anymore but they did make a 311 for a couple years before they switched the 311 to the Impact line.
Given a choice between the two I would choose a good condition but older Fuzion over the Impact. The Fuzion is a slightly better equipped unit than the Impact though after owning both I would say they are both nice and very usable. The Fuzion just has a few more details like bigger cabinets, day/night shades, nicer stereo, etc. Also, if you can find a Fuzion with a "Touring Edition" it is worth the money in my opinion. But essentially the Fuzion 302 (or 311) and the Impact 311 are the same model.
Oh, one difference I do like more in the Impact 311 is the bedroom/bathroom layout. In the Fuzion there is a small water closet for the toilet but the shower and sink are in the bedroom. On the Impact there is a separate enclosed bathroom which makes the bedroom more private, especially when you have guests.
I don't think you will be able to find something with a 2nd bathroom or 12 foot garage in a dedicated garage model at 35 feet.
Let me know if I can answer any questions for you about these models.
Eric
