Thanks mtbcyclist - as always great advice.

My thoughts on the enclosure are to go with MDF and then finish out with fiberglass, e.g., smooth out the edge from the MDF to the body panels with fiberglass/bondo. Hoping this ends up being easier than your project - and while I am learning about fiberglassing I will have an operational MDF box - which may not look great but should sound great.

Here's a snapshot of what I got done today:



As you indicated - there is plenty of volume available for a 10" - I will probably have to add sand as you suggested to get bring volume down to .6