You are going to get lots of conflicting opinions regarding size and type of tow vehicles, hitches, and size/brand of 5er. I'm a hoosier like you with a 37' 5th wheel and I've never had a problem getting into the Ind and Mich state parks. You would definitely have more choices of sites with a smaller trailer but we haven't had issues with ours if you can plan ahead.
We have a 3500 Diesel with a 6.5' bed for our rig without a slider hitch and haven't had any issues. Also have the gooseneck underbed hitch. We had a slider hitch previously and never used the slider feature so opted to skip that when we upgraded. 5er is a 2010 model so the nose is rounded which helps tremendously. You would probably be fine with a 2500 and gas or diesel would be personal preference. I've towed with both and my preference is diesel. I know some will say a newer model 1500 will tow your rig fine and that might be so. I would not feel comfortable doing it but that's just me.
