The mulch is fine. Dirts fine. Whatever you want to use. Boys are easy to accomodate.
With your "basking post," try and make it as multideminsional as possible. Think of a pile of debris that you would find lizards in out in a feild. Have you ever see a lizard out laying on a single flat rock in the middle of nowhere? NOWAY! He wants to have the option of disappearing to a lower level if its too hot out in the open, or if he starts feeling like theres predators about.
Now apply this to you cage. How can you recreate a similar environment? You can go find a bunch of logs and whatnot and just throw them in there. Maybe buy a few nice slabs of corkwood and put that in there too, to give some flat levels to work with. Just give em lots of options to choose from. Make it a very wide pile, so part of it is under the light, and part isnt.
Im actually im the process of changing my timors over to a more vertically oriented enclosure. Im anxious to see how they respond.
As far as mice. Buy a fuzzy. See what he thinks of it. You may be surprised.
After all, fuzzies are about the same size as large crix when you think about it. Theyre just a bit more substantial.
Ill get pics up as soon as i find my camera adapter. 