Oh, sorry!
Well, you should spot clean daily (pick up any poop you see right away with a tissue). And to be honest, the only time I've ever taken apart my vivarium was in January because on of my white's died suddenly. I cleaned everything as a precation. but, my vivarium is kind of it's own eco system. So I actually do not want to mess up the natural organisms that have developed in the enclosure. I have several live plants and worms in my substrate, and as long as there is no foul odor, I have not needed to do a full cleaning, except that one time.
Live plants are not necessary, but I've found that it is necessary for the natural ecosystem. they also help maintain humidity. If you use only fake plants, you may need to do a complete cleaning every six months? But I don't know for sure. Others will have to step in on that issue.
And if you can only get a 10 gallon, get a verticle one so your frog can spend some time climbing... But you'd be surprised, a 20 gallon isn't that much bigger and can easily fit on a dresser or table when standing verticly.