I did a partial floor repair in a Scamp
. The flooring was 5/8 plywood.
I joined the plywood with a lap joint. I used Gorilla glue which also acts as a filler when it cures with it's foaming action. I then used 5/8" long wood screws to hold the joint during curing. You may want to lay down wax paper or suran wrap under the joint to keep the gorilla glue from bonding to the camper floor. I am faced with the same repair you are currently doing in a Mini Rover (East Coast Trails West) I am working on.