Heat pad (flex-watt), and proper substrate will make an enclosure work.
Everyone says you have to use tubs BUT you dont if you know how to maintain the enclosure.
I have some in tubs and some in tanks or enclosures. Space makes tubs easier.
You can use eco-earth to really up your humidity, but a water bowl over the heat mat will also work.
Post some pics of your setup and we can help a little more.