I am also working on a DIY hood for my small tank.
I will be using Kilz which is advertised as primer and a sealer.
I'll use this for the under side of the hood and a satin black for the outside.
If you want to preserve the natural beauty of the wood, you may want to go with a marine type of sealer or spar varnish.
What ever you use, give it a few days after application to cure and gas off.
Really nice job on your hood.
March...