hot holding savoury pies on a propane cart - any suggestions?

We're adding a 2nd cart and expanding from crepes into meat pies/pasties.  We vend at farmers markets, no elect, gensets are frowned upon.  Cart #2 is a hot dog cart  w/ a 2 pan propane fired steam stable.  We plan to use it to hot hold our pies.   Problem is two pans only hold about 50-60 pies.  We plan to sell 100-250 on market day. We were planning to hot hold inventory in Cambros but experienced folks said the crust will get soggy. Could use an oven to reheat but  I cannot seem to find a reasonable propane oven or warming drawers so back to drawing board.  The only oven I've seen is a wimpy Coleman that is much too small.
 
Now I'm thinking of building 2-3 tier display case with tempered glass above the heat source and either converting to dry heat using a griddle or staying with the steam table and venting out the top.
 
This is a towable trailer so I'm worried about rock chips on the glass, etc. Leads on ovens or any suggestions would be very helpful.
Thanks!
Richard in Oregon