I am sure a gut can take a 300 to 350lb boar without a frame, a lot of his weight in on his hind legs as he mounts, perhaps when arching to get in deeper he pulls you in closer it may be heavier, but by then you are his anyway, enjoy him. I see some guys lower their front to get the weight more on their hips which are much stronger. I like a big boar, knows what he wants, where to find it, has a lot to give and jelly beads are larger to keep his sperm dammed inside of you and is not anxious to dismount. My likes anyway knowing the boar is big enough for me to feel submitted...a smaller frame just be careful, perhaps a frame is better for you.
I also like the feel of a large sagging boars prepuce pressing tightly against my anus, a good indicator his penis is larger and experienced