Cleaning these fermenters is quite simple actually. I have a rotating clean in place ball (CIP) that gets clamped into the 4" lid on the top. I'm using a high output sump pump to circulate cleanser through the fermenter. Just let it run for 10-15 minutes, then pass a fresh water rinse through, then a pass of starsan. Cap all orifices and it's ready for brew day.
I've contacted a cleaning product company that sells caustics and acids to breweries for their CIP systems. Their products need to be purchased in minimum 5GAL containers, but the prices are really good. $116 for 5 GAL of concentrated caustic cleanser, and $90 for 5GAL of acid brite to passivate stainless steel. I've also aske for a quote on their acid sanitizer, same idea as starsan.
Once I get pricing + shipping on all 3 products, I'll post on the forum to see if anyone would be interested in a club bulk purchase. I believe John and I will be splitting on 5GAL of each product, but we can order extra if you guys want to split 5GAL 5 ways or something.
According to the head brewer at the pump house, you can fill your keg with caustic solution, let it sit for an hour or so, and it is spotless, no need to scrub or anything. He told me this after hearing me complain about cleaning out kegs that were fermented in.