We actually use several of these racks in temperature and humidity controlled rooms. You could use pegboard but we've found that this might actually keep too much humidity in and as a result you could get mold problems.
We've used similar rack designs for our Ball Pythons and have found that a few of them do have humidity problems but nothing serious. We go through and spray down the cages about once a week and that tends to take care of all the problems. We just recently (about a month ago) moved our boas into the Boa Rack and so far I believe three of them have shed since the move...none of them had any problems.
The mesh we use is actually half inch plastic hardware cloth. Another solution is to use the hardware cloth and if you find that you have humidity problems, cover up the hardware cloth with plastic (i.e. flexible plastic sheeting, etc.). That way you could also control how much of it is covered up (1/2 or 2/3 of the top or something like that).
I hope this helps...
Celia
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Celia Chien
Celia Chien Photography
My Snakes
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