Everyone here is telling you these things for YOU. If they didn't care about you and the welfare of your animals, they would tell you to go ahead and do it, but it's just not a safe bet.
I experiment with reptile keeping as well, but I do it more responsibly. I keep all my species seperated and then do as much research on their natural habitat (as well as just doing some experimenting with temps, humidity etc.), and I am much happier working to figure out how to give my reptiles the best care possible as opposed to just trying to make setups that 'look pretty'. If that were the case I wouldn't think that my best setup design yet is the cattle trough in my basement, but it is.
I know you're going to take my post the wrong way, but just remember, people aren't saying things to make you feel bad, they're just trying to keep you from making a bad decision. If you really found evidence that somehow said your reptiles would do better in a group with other reptiles of different species (I have never seen evidence to suggest this), then you're free to do what you want. Technically, you're free to do whatever you want anyways...there are no regulations saying you have to do one thing this way or one thing that way, but there are helpful people that will lend as much advice as they can.