So you already have a disk compatible fork or you are going to purchase one for your tandem. I currently weigh 306lbs and have a 36 spoked Son 28 disk hub on my touring bike. I weighed 376lbs when I purchased the bicycle. I built the wheel with A very strong rim and it has not come out of true in over 7years of riding. I suggest the
Ryde Andra 30 rim. This rim is drilled so you have straighter spoke line with larger hubs. I believe bike 24 has them in stock.