I think I said it somewhere already, the strip foam is the easiest and fastest way I have tried so far.
I user 15mm wide and 5mm thick strips all over and I did not glue them together at all they are hold together by the double faced tape in the moulds, then the inside is glassed and the frames and all the other details on the inside are coved and glassed before the epoxy has set. That saves already a lot of time and sanding.
As I use narrow strips (15mm) there is no need to make them fit together. The only tool used when putting the strips was a sharp knife.
When the hull halves comes out of the mould and are joined together it’s about 30 minutes of sanding to fair the outside. Then a layer of epoxy mixed with filler to seal the foam and the joints, and then the glass laminated directly to that. It took me five weekends to make the Tabby.