The hot plate made to run on 220W with a 1KW element will indeed be very close to 50 ohms. Some reactance though would be seen though going up in frequency. For a fixed band use, say 20 meters, I suppose a L-C match could be made to tune out the reactance on that band, or just run through an antenna tuner.
A 1 KW hotplate made to run off 120 vac will be close to 14 ohms....use three in series for 52 ohms @ 3KW!
I would bypass the temperature control circuit though.
I once had a grocery bag of 47K 1/2w carbon comp resistors. I made ten 100 piece rings stacked one on top of the other, and immersed in a gallon bucket of ATF. It came out at about 55 ohms, but the shunt capacitance was huge! Had to use my tuner on 40 m on up.
Jim
Wd5JKO