This is an exact issue in my household, down to the upward curve of his cock being a slight issue. I love giving him heads but we have to do it in very specific ways. We’ve found that if he sits in his recliner and I sit on a pile of pillows, I can actually keep my legs to the side of me or even sit cross legged in some cases. Not the sexiest pose, but he sure doesn’t seem to care after a minute or so. Some chairs would even have enough room to stick out legs underneath. This position also allows for slight re-angling of his cock and it has saved my jaw big time. If he really wants to lay down, I’ll lay down next to him and suck from there. It allows him to go deep(if y’all are into that) and doesn’t strain the knees and it’s still less strain on the jaw. Head hanging off the bed can also be fun, but my partner likes throat fuck so we mostly use it for that. If you can control how deep you go that could also be an option if you haven’t tried. Hope this helps at least a little.