Been to Diamond Lake/Crater Lake many times.
Diamond Lake CG would be tough to impossible to navigate in some areas.
Broken Arrow would be real easy. Most sites are large and would accommodate a 35' 5er easily.
Never stayed at the RV park but have rode our bikes through it. 35' would be no issue there either. But you'll be sardine canned in.
Diamond Lake is really pretty in the summer. Lots of outdoor things to do. There's an 11-12 mile paved bike path that circles the lake if you like to ride bikes.
Crater Lake is only a few mins away. If you're in good shape physically I'd suggest doing the boat tour. There's some really interesting sites around the lake that you can't see from just driving the road.