Just a final report on my situation. I have located a "pure sine wave" inverter. It is an Eliminator brand sold by Canadian Tire in Canada for for $180 (on sale from $300). I called the company's 1-800 number and explained my situation and they said it should not be a problem to use it in my situation, that is plugged in to the house panel. I tried it and it now works.
Thanks to all for your advice and help!
