if you havent already, post this in the clyde section, at least there you hopefully will get real life experiences with X wheelset for riders of a given weight.
Do remember that with wheels, who puts them together and the attention to spoke tension plays a big part in how strong the wheel is, although it obviously makes sense the route of looking into tandem wheels.

the trailer idea also seems like a good idea, a bunch of weight off the wheels of your bike. Downside of course is the extra expense of a trailer in case you find you really arent into touring, mind you they probably are not that hard to resell.

good luck with getting riding more and finding a setup that works.