: I have a framework of two by twos suspended about seven ft high
: above the strong back area. The frame is about 23 ft long by
: about 8 ft wide. Over this I have taped one and a half meter
: wide lengths of bubble wrap. They form a ceiling above the boat
: and hang down to the floor. The strips are taped up with packing
: tape to keep the whole thing fairly airtight.

: . . .

The bubble wrap is a good idea. To save time and effort and get to building the boat a bit quicker can get nice temporary car garages that close up, and bubble wrap is sold in large sheets for use as swimming pool Summer covers . . . you can also get propane heaters that run off a BBQ tank; I have one and it heats the workshop in 15 minutes.