I would make it an All-In-One style tank if you are going to put in the back panel, then you may as well make the filter yourself. (just a few more cuts of plexiglas to make some baffles to direct the flow. For filter media I am using a prefilter sponge, Purigen, Ceramic beads in the intake section. Then the water is pulled through a sponge filter, then heater and then is the return pump.
If you wanted to use a canister filter you could skip the back panel, and just stick the input and output for the canister filter at one or the other end. as long as the canister has a high enough GPH rating it should filter fine.
Both filters basically work the same way.