Just throwing this out there,
If you are going to use 20" wheels and you want durability, look for a set of front 20" Mag rims (5 spoke type) with sealed bearings.
Should take a good load and virtually no spoke breakage problems, should be pretty easy to find an spindle axle to fit the sealed bearing
http://www.bikepartsusa.com/Product-...in-Z-Mags-prk/
