After weighing my options, I think I'm going to setup the 35 hex as a paludarium.
I'm an artist so I'm excited to get in there and put my sculpting to use in designing the landmass and water feature. I also think it'd create a very interesting home for a dwarf puffer. Those little guys won over the lady so she's lobbying for one. She'll get her fish, I'll get to avoid the CO2 hassle, and the light stays and is actually beneficial to the setup.
I'll create my little aquatic garden in the other tank, a 40g breeder with (4) 21w t-5's and an eheim 2126. It will definitely be easier to prune and maintain than the taller hex.
Thanks for all the input guys, it's appreciated.