I also use an electric mattress pad. Remember; heat rises. An electric blanket will send a lot more air up
into the room than it will down onto your body. With a heated mattress pad, the heated air moves up into your body, and your regular blanket holds the heat in. It's so efficient that I only use mine on the lowest setting. Mine is made by "Sunbeam", and I think I paid about $60 at Walmart for the queen size. I have a 3" memory-foam mattress topper under
my Denver Mattress (like a box spring). The sides of the mattress pad are tall enough to wrap around both the mattress and topper, and tuck in on top of the plywood bed support.
As for the heater, I use a portable electric fireplace in the living room. But I turn it off when outside temps get near freezing. Found out the hard way that if your furnace isn't running, your underbelly won't be heated, and your water lines will freeze! I turn off the heater at night, set the furnace thermostat at around 65 (the trailer gets down to about 55), and turn on the heated mattress pad. Both the dog and I sleep like babies.