I have a 15' x 48" metal frame Intex, that I heat with a DIY wood heater. My usual wood source is broken/discarded pallets, and any other free wood I can get. Works quite well, using the "tower" pump that came with the pool.

Weather lately has been somewhat cool, lows in the upper 50's to lower 60's, and I'm able to keep the water a nicely swimmable 85-95, with keeping it covered at night.

I don't know if this would be something you could do, since you are in an urban environment, as it does get a bit smoky at times.

If you want to know more, just ask!