Levi,
I predict that the wood will be set on fire and, likely, punched completely through when the motor lights.
This is a "Q" motor . . . Chuck's is an "R" motor, much bigger, with an "S" motor following it !
You're going to need a "blast deflector" to protect the deck ( fire ) and sides of the trailer ( damage to the paint, wiring, brake lights, etc ).
I am envisioning a "Chute"-shaped design that would contain the flame and exhaust and direct everything aft, beyond the end of the trailer . . . Maybe something like this ( concept only ), 18" - 24" wide, length as required, with a "U-shaped bend". ( "Concept" in images below ).
Side Panels . . .
Picture something like this, with side panels . . .
NASA Sketch . . .
This thread really shows the basic concept well . . .
https://forum.nasaspaceflight.com/index.php?topic=36733.40
If I have to, I'll build a cardboard model to illustrate clearer.
Thanks, Levi !
Dave F.
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