I've found that the snowboarding gear companies have stuff that runs big, but they still have the smaller than normal waist (I'm looking at you Special Blend, how do you call 36-38 an XL).
The only pants that I've found that has a wide waist to match the wide leg were Zumiez store brand pants. And a pair of Spyders. MarkerLTD (the outerwear company, not the shit binding company) also has more "regular" waist widths.
THERE ARE SPECIFIC REASONS AS TO WHY I AM MORE LOCAL THAN YOU
I couldn't find anything in Burton larger than an XXL for a man which is chest size 44-46" waist 38-40" tall inseam 33". I'm internet shopping burnt out so I could be wrong.
But I found that Spyder has a 3XL where the chest is 52-54" and a 3XL in pants where the waist is 44-46". Their stuff is good quality too. Having a hell of a time finding an actual link for you though.