Buy whatever you can find that has all the things you've asked for, even if you have to handle some of the features as after-market add-ons. You are in the right price range for 2-5 year old 45 footers, and at that level make or brand does not matter much. Newmar, Tiffin, Travel Supreme, Thor, Winnebago all build in that size and price range, though at 45 feet you may find the premium brands more available. Go back a few more years and you will find upper-end models from Monaco Corp brands, and many buyers prefer that chassis. But that also takes you into "the company is out of business." In some cases, they have been bought by somebody still in the business, with brands changing.
That size and age range, it is going to have a lot of slideouts or some really big ones. When you get into floorplans with huge slideout space, your problem may be satisfying the "access to all main areas" criterion. That one is going to be taking a lot of looking, and it would be helpful to be in a place where there are quite a few large dealers to work with: Central to South Florida, south-Central to eastern Texas, or Arizona.