In a pinch, I’d suggest powering the electric off of an uninterruptable power supply. It isn’t much wattage, with the most being the bulb in the oven, and the UPS filters the power through a regeneration step. In the boonies you may have a lot of spikes in the supply.
Generally speaking, just about every “small” ups does not do isolation nowadays. They are “offline”, meaning the output is the input till the MCU in the UPS detects a disturbance outside of its operational parameters. There is a transfer time that indicates how long the MCU takes to make the decision to transfer the load to the inverter, and how long it takes to set all the internal relays and power semiconductors, and how long it takes for those devices to settle.
If memory serves,that can be around 40ms or so. A full 60 hertz cycle is 17ms. Generally, that’s not long enough for the caps to discharge too low in most power supplies.
But there is a gap of no power, and there can be a gap where there is a spike a well. Additionally, most UPS have surge protection devices built in to limit spike damage, however, beware that just like a surge protector, you need to replace your entire UPS every few years. Honestly, it would be better if you could purchase units that allow surge protector module replacement. The inverters last forever, if the unit is a good one.
If you want a true isolation unit, this is called a double conversion unit. Very pricey and generally not found in small sizes, and they burn a significant amount of extra power for the double conversion.