For our 4x2 PVC enclosure we use a Reptile Basics 80 watt RHP as the single heat source. It works great. Hot spot is 88-99, ambient on the cool side is around 81. RHP's heat up objects moreso than the air, so unless your home is kept pretty cool, I'd think having both a RHP and UTH would be overkill. Our house is around 74/75 in summer and 70 in winter. Thermostat for RHP is currently set to 87, we'll probably have to bump it up when it gets cold out.