So I have a new idea! Currently I have a 40 breeder with 3 firebelly toads and about 15 endlers(they keep multiplying!) I siliconed a divider in and have a piece of driftwood in front

Don't mind the light. I changed it!

So, I don't have much vertical space in the land area for plants. I'm thinking of upgrading to a 65 gallon!
My idea is to put maybe a 10 gallon tank inside the tank to make a "removable" totally separate land area so there's no need to worry about silicone. This way there will be water on the sides instead of seeing silicone and dirt like I do now.
I'm thinking of making a waterfall on both sides of the land area.

Has anyone done this? Stupid? Any better ideas?