Waterproof maintenance hatches--simple, durable, 4" ABS plug?

Everything on my boat is meant to be watertight. I already experimented and made a larger hatch for a forward bulkhead--routered channel for neoprene gasket, t-nut insert, fitted hatch. However, for some smaller hatches (very infrequent maintenance only) that will be in the back of the rear holds I'm thinking just 4" ABS female insert with a threaded plug. The female insert would be trimmed flush etc and set into a hole in transom. Transom is composite 3/4" marine ply and 1/2" western red cedar. Of course with proper surface prep on the ABS--alcohol wipe, flame treatment, G-Flex epoxy, etc. These plugs are INSIDE holds which are intended (not built yet) and designed to be watertight and will allow access to the rear air boxes. Hatches'd only be opened to possibly help feed wire up to the radio tower/rack and possibly if 316 stainless fittings on those airboxes for towing or drainage ever need plumbing work or replacement.



Is there anything better than this? Lightweight and durable are my most important considerations on this boat. For wire channels, etc, below deck in the foam or whatever do people just use stuff like vinyl irrigation tubing or PVC?

This is the actual boat design/build thread: Custom 19' all weather, minimalist, strip plank composite 'go fast' https://www.boatdesign.net/threads/custom-19-all-weather-minimalist-strip-plank-composite-go-fast.66022

 

They make purpose build watertight inspection ports for small boats. Here is quick google example...
Deck Plates | Inspection Hatches | Port-lights | Five Oceans https://www.five-oceans.com/collections/deck-plates-hatches-portlights?page=1

 

Hmm, okay. Those are cheaper than 4" ABS plugs and female inserts. Thanks. Stoopid, I should have just googled. I bought an Armstrong round hatch in the beginning to see what it was like and it was pricey.

 

Threaded plastic fittings have tapered threads, as do most plumbing fittings, and can be a real b—-ch to remove when tightened down to leakproof status. I’ve had to cut them out on occasion, after shredding the wrenching lugs.
Maybe if installed with silicone grease ?