My advice is a cheap bike with fat tires. On mine I put a Jaand Mountaineering back rack which is longer, wider and stronger than most, and I use Jaand fabric grocery baskets - very large and strong, and come off when needed.

Another option is to look at the Wald website. One could load their bike with huge double wire back baskets, a wire basket for on top of the rack and one for the front. You could carry four full size paper grocery bags this way. Wald makes more baskets than you could ever need in every size. Let me put it this way - they are very popular in China.

Or just buy a trailer...

Clay