19' Flats Boat

What's your aversion to wood? Building it of good ply then 'glassing over it would be pretty slick imo; much, much simpler and less expensive for the type of boat you're wanting.

 

I've been on an XF20. It has huge deck space. on the Bateau forums there's a picture of it with 19 heavy guys all standing on it at once. 5 is no problem. No gelcoat over epoxy, though. I've been told it has poor adhesion. You should do some further research about using 2-part paints. They are now very high-tech. I'm in the middle of using Perfection.
Jawues may balk at the idea of a 115, but I'm puting a 115 on his OB19. The XF would handle it fine (even better), but might increase draft/resting trim somewhat.

 

I'll vote for wood as well, the paints mentioned will look like glass if done properly. Maybe the OP has a chooper gun, and builds molds, but I don't get the cost of plans being a big deal being less than the cost of gel coat fo a boat that size.

I'd consider having it done in aluminum as it looks like the breaks are not that complicated, might get the bottom in one piece.

But if this is a budgeted project, wood would be the way to go.