Cockpitfloor flange + plenty glue
Cockpitfloor glued and temporarily held in place with woodblocks and a piece of wood between the beam bulkheads to keep the floor straight.
As I'm almost done taping the interior panels, I have to prepare for the dreaded longboarding. I'm experimenting with a poor-man's longboard: it's just a piece of foam with one layer of tape on top and two wooden blocks as handles. I tried to glue sandpaper with spray glue, but that didn't stick. After that I used ready made wallpaper glue: this works ok but takes a while to set enough. If the longboard works well, I'll make a few so I'll never have to wait for the glue to set.
Once I've done some sanding I'll report if the longboard works. I hope so: it's cheap to make and VERY light.