Nobody's wrong in what they've posted about co-habiting. It can work - and it can go horribly wrong. It's a bit like "Big Brother" on TV - sometimes the housemates get on, sometimes they don't. Since the average contestant (and viewer) have similar levels of intelligence to a reptile, the analogy is a good one....
There are some other species that could go into the mix and could be worth considering in a 4x2x2 viv. There are loads of geckos that aren't commonly discussed, but that would live happily in a viv of that size. A chuckwalla is another possibility.
I'd recommend going to a large reptile shop and having a good look at lots of different species. See what takes your fancy.
Draco dormiens nunquam titillandus
“... there is no shame in not knowing. The problem arises when irrational thought and attendant behavior fill the vacuum left by ignorance.”