When I was a kid we used two of those big 23K BTU units to help supplement the steam radiators in our big barn of an uninsulated Victorian.
Over time, they left a greasy film on the windows and walls, probably from being started or extinguished inside.
I was, for awhile, seriously considering getting a small 10K BTU one (round one, not one of the square radiant units) to supplement my heat pump, but I always held off because of the experience of using them as a kid.
I finally sprang for the pellet stove. Best thing I ever did.
If you have the money up front, you can get a decent pellet stove like my Castle Serenity for $900 to $1k on sale. Figure another couple hundred for the pad, exhaust venting, and installation (if you don't install it yourself) and between $4 and $6 for a 40 lb bag of pellets.
Depending on how much you pay for heating in the winter with resistance electric, you might be able to get your money back in just a couple of years, and you'll be a lot warmer is my guess.
You can set the electric to basically freeze protection level (I keep my heat pump at 60 in the winter and it only runs when I'm on vacation at T-giving and Christmas) and run the stove when you need it.