Hi Bob,
I built my 18' Guillemot starting Nov 1st. last year. The only thing I noticed during building was that the glue did not dry as clear as it does when it's warm. My shop (in the basement under the garage) is unheated and I used a wood stove on occasion and typically used a kerosene heater. I heated the shop while I worked and shut down when I was done for the night. I don't think it ever got below 40°. Once I got to the glassing stage I broke down and got a propane space heater. I tried to keep the shop in the 60's during most of the glassing process. I'm sure I did't do that great it stable temps but all worked out well. I've built two in the summer months and one through the winter. Summer is better. If the wood stove was a good one I think it would have worked quite well, but it's old, has holes in it and now is nothing more than a storage bench.