When I take it up the butt which I love, I like to make sure the top gets full pleasure by not coming myself till he's fully satisfied. It makes it more intense for the feeling.

If you try positions which enable him to penetrate and minimise ramming the sidewalls e.g. doggy style you may find it more comfortable. Also use a decent lube like liquid silk, vary how much you put on depending on size and how rough a fuck you want.

Hope this helps and if anyone wants to try it out on me message me!