You should place the RHP on the ceiling at one end of the enclosure. They don't get hot enough to burn your snake. The enclosure temperatures will drop the further you get from the RHP creating your gradient. You should use a pulse proportional thermostat because they maintain steadier temperatures and prolong the life of your heating element.
My thermostat is plugged into a surge protector. I don't know if that makes it safer. I put it in there because I needed outlets.
I wouldn't add vents. Retaining heat and humidity is the most important thing with BPs. Unless, you're planning on making your glass front airtight, you'll have adequate ventilation.
I use an 80 watt Vivarium Electronics RHP that I got from Reptile Basics in my 3x2x2 plywood enclosure. You can see my set up here and here.