Why is a big guy riding a bike quite hard, using 32 spokes?
If you can get hold of a 36 spoke hub, you problems will be over.
Most of the strength of a wheel is due to the spoke count and the build quality.
Spoke quality will help prevent spoke fatigue (not a problem if the wheels Taco first!!), and rim quality is less of an issue with disk brakes. You wont wear down the rims by braking, so thin-walled rims won't become dangerously weakened.
Get onto Canondale for a suitable 36 spoke hub, and get a good LBS to build it up with eg DT 13/14 guage butted spokes in a standard 3x pattern. Rims with the spokes offset from the centre will build up with less dishing, so will be a lot stronger. Bontrager make rims like this.
In the good old days, hard riding, loaded tourists used a 32 spoke on the front, and a 40 spoke on the back.