So I ordered a foot warmer and finally a hi/low plug to control the temp a bit and it's working out great.
First I ordered the foot warming pad off Amazon to try out. It only draws 90 watts with a temp of 130 degrees. After using it a bit I found that 130˚ is a bit too high and I would alternate between pad on and pad off once the clay got too warm. Since it was working well, I went ahead and ordered the hi/low plug attachment from Amazon. I only used it a couple of days and already know it was a good addition. Once the clay reaches a toasty temp on Hi I turn it to Low to keep it warm without melting.
All in all, I'm very pleased with this new system. I place tinfoil on the heating pad and then arrange chunks of clay on the foil- as I take warm clay off the pad, I drop more cold clay onto the pad.
It does take a bit longer for the pad to warm up the clay than the light-bulb, but it is more consistent without the burning/melting hotspots. Only real drawback is that the clay really needs to be in direct contact with the pad surface so you are more limited in the amount of clay you can warm at a time. In the future I may try putting the pad into a styrofoam box to trap the ambient heat and put in more clay but for the moment and for the cost, this is working quite well. Especially in winter in Colorado it is so much nicer to sculpt with buttery-warm oil-based clay than hard chunks.
After years of using my original clay warmer hot box, I decided I wanted to try something new and more energy efficient. Plus, while the styrofoam hot box works really well, it can sometimes work too well, especially for softer clays like Chavant's Clayette in Soft and cause them to melt or have hot spots that can burn your hands if you aren't careful.