Being on top problem

So I’ve been married almost two years. I’ve never been successful at riding my husband. I tell him it’s like climbing a tree to get on him, lol. He is 6’4” and definitely lives up the stereotype for big guys (ya feel me?). His hips are so wide I have to almost do a split to get my legs over his hips. If I can get in the position, I always get a cramp (pulled muscle feeling) in one of my hips and I have to jump off. I want to be able to ride him and although he doesn’t ask for it, I know he wants it too. Any tips? I’m not a small girl, I’m5’7”, but his hips are soooo far apart, my legs can’t spread like that lol. Would stretching first help or is there something else I can do to help prepare my body? Any position modification ideas? Thanks!