We've been happy with both of our FR products, so would suggest a look at one of the FR Rockwood Mini Lites. Absolutely a slide. You'll end up with a more square layout and I think it would feel larger, but you'll be towing short. We had a ROO 23SS and loved it. It was a perfect size for us with the large slide....until the high-tech hip, the vanishing cartilage, other misc old-people stuff, so we moved to a Rockwood Ultra Lite 2604. It's plenty of room for us and is towable with our '03 F-150 with factory tow. In all honesty, the 23SS was a perfect size (it's really a bit over 20') but the hybrid gains you some space. We never intended to make a move. The size range you're thinking of is nice and easy to get into most any site you want.
You do realize that as this thread grows, so will the length of the trailer you absolutely must have with at least 3 slides....just sayin'. And you'll be to a 350 dually, of course. Good luck and happy camping. Let us know how this progreses.