Re: mirrocraft v-hull ... add a floor ??
If it's an aluminum boat, I have two buddies who put floors in their 16' Mirrorcraft boats. Both of there's use many rounded top ribs and no stringers.
What one did was to lay a center 2x4 along the keel, and two outer 2x4" laying flat on each side. He made three panels which set in place with no fasteners. He notched the outer 2x4s to fit slightly over the ribs on each side. The keel runner sits vertical. Each panel is also framed on the edges underneath with lighter wood. It makes for a very usable set up and since the panels are removable, they can be stored indoors when not in use and you don't have to worry about dropped bait rotting under the floor.
Another buddy removed his seats, ran a slightly taller keel strip out of aluminum, then he cut and riveted in 1/8" thick aluminum diamond plate with foam flotation under the deck and foam pipe insulation filling any side gaps to prevent anything from getting under the sides.
He then camo painted it along with some sand for traction. I like that set up the best, it's clean looking and light. It's also super easy to clean and will no doubt last forever. He mostly only hunts with that boat but does do some fishing. Both are Mirrocraft Lake Master hulls from the early 70's.