I've never camped further West than Kansas, but we've never had any problems with campsites. We started with a pup, then an 18 foot TT, then a 31 foot TT, and now a 35 foot tt. The key is to scope out your potential campsite before you get there. Most campgrounds have an internet site that will give size restrictions. Even with that, a call to the campground may be needed to clarify exactly what they mean when they say 40 feet. Is 40 feet the length of the pad, or is 40 feet the length of the camper (and then the tow vehicle can also park there). Pre-planning research is necessary, unless your camping with a 12 foot pup or tent, regardless of how big or little your TT is.
I purchased my Outback this last September, and we had it out the next 6 week-ends in a row, all over Indiana. Then we went to Florida (from Indiana) over Christmas week. We stayed at a motel on our way down and a motel on our way back, a KOA in Georgia on our way down, and the 5 nights at a Florida State Park. I had no problems parking, driving, or maneuvering anywhere with that 35 foot TT. I will say, I was a little challenged getting into the camp site in Florida. On the surface it looked really simple, and for a shorter trailer it would have been. But with a little bit of maneuvering, got it parked just fine. Then I was concerned about hitching back up and actually pulling out. But it worked out just fine, actually it was easier than I'd anticipated.
Longer trailers are a bit more challenging. It does take a little more patience, a little more planning, and a little more common sense in understand how sharp you can turn, the limitations of your rig, and confidence in your own ability. If you have a positive-confident attitude, you CAN take a longer rig almost everywhere.
Funny though, we went to this one McDonalds on our Florida trip, thought I could swing completely around the building and come out the other side. Got behind the building and it was a closed parking lot, surrounded by "nothing"! I was in a real pickle. I got out of the truck, sized up the situation, and actually backed the rig completely out to the street. Yea, it took a little time, a little patience, and required I get off my butt and actually open the door and get out and look behind the rig and see where things were (as cars were coming and going, and parking, and everything else), I got out without any problems. I just had to take my time. I think that's the key! When driving a bigger rig ... take your time, be confident, and RELAX!