Product review (3 stars): I should've gotten a chest freezer instead.
I highly recommend you DO NOT attempt to modify this to work with a 5 gallon (or two 5 gallon) kegs.

First of all, the threading on the C02 regular is backward.  So your replacement part list of very limited, and your solution to work around that gets bulky incredibly fast.

Next, the tap tower.  There aren't replacement tap towers that have 2 feeds.  Which means attempting to have 2 beers on tap with this product is not going to be possible.

Aside from those two very large (deceptive) selling points, this product will work just fine.  My advice, plan on changing absolutely nothing about it, except the tap handle.  That you can change at will!  Everything else, leave completely alone, and don't trust the gaskets alone, still use Teflon tape.