The only problem I can see, is that unless you may have a problem getting to equipment since on the sides it will locked in. if you can get to the back it won't be an issue. I have a similar idea with a water fall (a 75 gal drilled out on the back and bottom) and a 55 gal (planted tank). The viv is for my dart frogs and the platned tank is for a peaceful community of tetras
Bunches of tanks.
Reef, Planted, vivarium, terriarium, salt.
I worked my self up from nothing to a state of extreme poverity