Phil,
I'll be building mine for "C" Class, so it will be slightly different - no stringers for a start.
I'm debating whether to strengthen it or not. Resin on its own will make it more rigid, and heavier, but probably not much stronger. Polyester resin on its own is pretty weak, so another layer of layup would add a lot more strength. Or maybe mix chopped strands in with the resin, and paint it on.
If you do slosh the resin around, try to make sure it doesn't pool too much anywhere, or it will tend to get rather hot as it goes off.