what wood for hatch combings and rims

hello.
Im building a decked whitewater dory. i am about ready to start making hatches and combings for the decks. what wood is everyone using for combings and hatch rims. the hull is 1/2" and 5/8" corcell and the interior is 3/4' plascore. the hatch lids will be made of plascore but will have wood rims. i made gutters and hatch rim landings using foam core, but i would like to keep the combings and rims out of wood for its strength and durability, etc. everything will get lots of glass afterward. Ive used fir in the past on oiled drift boats but found it to cup too much. I'm sure encapsulating in fiberglass will help prevent warp, but dimensional fir is not my first choice. I have some plywood that was given to me with my last boat. i was told it was marine ply but after cutting a few strips for hatch rims i noticed small voids in the core which makes me feel like this is just regular old 1/2 plywood and not marine ply (marine fir SHOULD have no voids right?). i am now reticent to use it for fear of cupping later on. so what do people recommend. i need something light weight, fairly hard and warp resistant that takes fiberglass well. I thought about bugging some of the local cabinet shops to see if they had any higher grade plywood, also can find mahogany locally, but that is about it. anything else needs to be ordered in, and I'm almost out of foam core so thats not really an option as ordering more would be way pricier that just framing with wood.

what say ye boatbuilding experts?

 

White pine glues and works really well and is lightweight.