Bob makes some good points, that if everyone ignored would likely result in no more Burning Man...(due to the MAN)...and many sick/dead people.
...from a practical standpoint, however, if no one knows about your isolation tank, there will be no one to complain/issue a citation...so if you just want to gift a dozen or so sessions each day to people whom you meet, with discretion, and mind the sanitation guidelines (like it sounds like you will), you should be fine (tell no one). The incoming inspection could be tricky (will the tank be full as you go through gate?). Camp showers are the same, really, or should be (some of those are NASTY and microbes are not bound by the Courts), but since camps are a "group" all "living together" they are held to a different standard (but how many camps have allowed people not camping with them to use their showers?)
If, however, you want to have a sign advertising your service with people lined-up out front waiting to get in, or have a listing in the who/what/when guide, then your only option is likely to go through the health department, jump through some very high (and possibly expensive) hoops, and get permitted. Be prepared to submit a lot of paperwork, pay fees, wait for inspections, etc. Getting placement/clearance through the Artery as an official Art Project may help (ie-submit an application).
Good Luck! sounds like a neat, "legal" way to experience expanded consciousness at Burning Man!