I had to butt join an extra board to make the 430 mm width out of the cut offs available.
Here I'm applying a sealing coat. If I find it satisfactory I might try to use wax instead of packaging tape as a demolding surface. Temperatures are falling down ( although they have been in the upper 20's till the end of September !) so it's taking longer for resin to cure. Tomorrow I hope I'll be able to sand the mold and apply another resin coat and test if the wax option works.