[Milsurplus] handtruck, wagon etc. suggestions?

[Hue Miller]

Mainly for hauling heavy metal from the car to hamfest table,
what do you use, that works and works well?
I have borrowed from work a folding handtruck. It's quite light
and folds down in 2 dimensions but - with handtrucks, the 
weight bearing surface, "nose plate", is never really large enough
and not ideal for our subjects, which are not mostly boxed items.
My criteria are, not real heavy, I mean around 30 lbs at most,
collapsible if possible, and tires that are no smaller than say,
8-10 inches.  Caster-size tires do not work in dirt parking lots,
especially in the Northwest, where you might also have to ford
some large puddles in the parking lot. I suppose maybe some 
kind of wagon would be best, rather than the good old fallback
handtruck? I don't need to have more than maybe 150 lbs per
load, but figure many of the riders will be boatanchors. 
What works well for you?
thanks-
Hue Miller