Converting dry box to fishbox?

[Nasty]

What would be some problems I should worry about if I convert a dry box into a fish box? First of all, it would drain into the subfloor (hull). Could this cause a problem? Next, I would have to drill the drain holes larger-- probably the size of a 1inch drain plug-- so I can plug the holes when there is ice/fish. Finally, I would have to put some sort of insulation on the inside of the box. Anyone tried this before? What do you'll think? I want more walking room... the 100 quart is getting in the way.