Shop wheels

[HRBS]

plywood is not structural

Not to get into a pissin match but plywood when placed vertically IS very structural. TJI trus joists are a perfect example of that theory (I have a background in Architecture).
Anyway back to topic, John, you may want to invest in a set of these for your next project:

http://www.kugelkomponents.com/products/mockups.php

We use them all the time during mock up. They not only support 1500 lbs but are light weight and skinny which make storage pretty simple. Dont cheap out on safety !
Good luck with your build !