Yes you can place acrylic plates in the bottom to cover holes. I would not try to bond a whole sheet to the bottom unless you use a thick product like sci grip #40.
Be sure the surface is very clean to get a complete bond.
I bought a used tank with 4 holes in the bottom like that. I patched 2 and left 2 ran a closed loop for more flow. I really dont like holes in or near the bottom of a tank. Too much bad can happen if you have a leak.