I have my bp in a tank just like the one you have, and to keep my humidity up I bought the Tropic-Aire humidifier and air exchanger and since then I don't have any problem with the humidity. For the temperature try one of the petshop's bulb because I have one 75watt and a small uth on the warm side that I bought on petco and is working fine for me.
Hope that this can help you
Jesús