Since building my enclosures with Expanded PVC this year, I would suggest a plastic enclosure, I spray my Colombian Rainbow's enclosure once a week, at most (infact its been 2 weeks since its last spray, currently reading 85%). despite not spraying very often, the humidity has not dropped below 80% at any point.
The enclosure is also planted with live ferns and moss, which does help keep humidity levels up; but even so, plastic enclosures are excellent for high humidity species, with little need for foggers and rain systems