I suggest 24 spokes radial and with a very light rim especially the rear wheel. That will give you more incentive to keep loosing weight.
LOL Well at least it will force you to WALK a lot more than you anticipated!
I've had great luck with a Kona Hoss and am in the process of upgrading the rear wheel to 36 with a heavy duty rim from the factory 32. I found I was busting about one spoke a month, but also that I had to baby the bike too much esp. when carrying a loaded trailer. The 36 will free me up from these concerns.