No chemicals, no electricity, refill and clean after each stay, and “environmental friendly”.

Information is readily available, and I understand it can be difficult at times to discern the trash, the selling from the substance.

We do not drain our hot tub after every guest, but we do test and adjust the chemicals, vacuum it (sand) and skim the top if needed after every guest. 

If I were you, I'd go for the heat treatment as long as it's immediate and kills eggs too, because chemicals need to be reapplied. 

I have learned to get a cheap maintenance person and have them buy the good chemicals from A1 Able and spray it for you.

That includes weekly cleaning, chemicals, flushing of filter when it needs it, topping off the pool, and my people clean the pool deck when it needs it.

I used to work for a start up, we sold maintenance software to big oil and gas, chemical companies and other big producers.

Plenty of good, normal people have gotten caught with substances that are largely legal now but weren't always so legal.

I wrap them in tar paper or brush on actual tar or similar substance.

It's the substance of the transaction, not the structure.So, the inquiry becomes not whether you are representing others and engaging in 6 defined activities but simply whether you do 2 or more deals involving real estate in 12 months.