If you haven't tried NF, I had good luck with their pants. I have pretty large legs/backside and they worked for me. The leg taper looks nice too. Take a look at their size charts - they give a range of fitment types based on size. I sized up for a looser fit and I'm happy with them. Might be hard to find them in stock though, I signed up for stock alerts on their site.
Try the Leatt Gravity 4.0 pants in the XXL. They say that they are 38s, but fit more like 40s and feel abit more roomy, esp if you are wearing crash pads underneath.
Also, check out the Fly F16 pants…abit on the heavier fabric side but fit nicely in the larger sizes.
Back years ago, NEMA made some really good (and well priced) DH pants…can’t find them anymore though.