Interesting! No, I haven't done it, and in fact I've never even had my own real evaporator like that, but it does seem like the worst that could happen is you warp your cover, which I think is pretty likely actually, but you'll no doubt be keeping your fire much calmer than if you were trying to boil sap. Won't be super-efficient since the sides will be insulated and there's probably no damper, etc, but it would certainly be warmer in there than without it, with potential for getting too warm. Definitely don't try it without the insulation because the sides of these units aren't meant to see flames. The exception would be the evap-o-grill which would be a worse evaporator but a better wood stove than the other evaporators you mention. In any of these cases I wouldn't leave it unattended until you are very familiar with what happens.
2024: 28 taps, 7 gallons. RB5 purchased but not opened :-(
2023: 30 taps, 17 trees, 11 properties, Sugar Maple & Norway. 2x3 flat over propane & kitchen finish. ~11(!) gallons.
2022: 9 taps, 5 trees, 4 properties. 3 hotel pans on 3 Coleman 2-burner stoves burning gasoline; kitchen finish. ~3 gallons.
2021: 2 taps, 1 sugar maple. Propane grill then kitchen finish. ~Pint.
All years: mainly 5/16" drops into free supermarket frosting buckets. Some plastic sap buckets hanging on 5/16 sap-meister.