This is what I can tell you. We use vinegar and water to clean the evaporator and pans and rinse well. It's a different vinegar only in that it does not contain spices. i have used a five gallon pail that was washed several times, and allowed to air dry for 6 months, then washed again. It is still being used to collect sap from trees with no effect on the sap. The BBQ buckets will be easier to clean out, but may always have a reddish orangeish tint to them. In my opinion, and others may not agree, if you think they will work and you can spend the time cleaning them, go for it.
2004 - 2012 2x3 flat pan 25 to 60 taps
2012 2x3 new divided pan w/draw off 55 taps
2018 - didn't boil surgery - bought new evaporator
2019 new SML 2x4 raised flue high output evap. 65 taps
made 17 gal. syrup
2020 - only put out 53 taps - made 16.25 ga.l syrup
2021 - Didn't work out
2022 - 25 taps on bags / 8 taps on 3/16's line - late start