My take on delaminating edges when cutting is…as long as the bits fit, you can slap the glue and filler on afterwards and it will still be strong enough. Put some supporting bits of strip balsa behind joints if worried.
Boat looks good so far.
All my landing craft were built from 4mm ply of varying quality, butt jointed with PVA glue, and finished entirely with household grey primer. No fails yet, no splits or cracks, no leaks, completely waterproof.
Ashley