lj2654, we started with a 42 ft. Dynasty and never had a problem going where we wanted to go. We moved up to a 45 ft. (didn't want Dennis to have a longer motorhome, ha!) and still go where ever we want.
Now that we are 65 ft. in length, a pull-through site is always desirable but not a show stopper if I have to unhook. I don't think you'll find any problems going where you want to go as you are used to 40 ft.
With a 42/43 ft. unit, you probably will not gain any under bay storage because of the now added tag axle. But you will enjoy the stablity that the tag brings. A tag helps the motorhome go straight and speed bumps are softened with a tag. It also helps hold down porpoising (it's what I've read but we have always had a tag).
As long as the unit has good service records, the miles are not a problem. We did have to have 4 anti-freeze boxes (including the original). Finally, the last one was the charm.
Good luck,
MM.