I set my tent up wherever it will fit - on a white carpet if asked - I use a big black towel in the base of the tent and a smaller one just outside the tent for clients to step out onto.
I decant my solution into cups at my house or in my car and NEVER pour soloution into my cups at a clients house. I have lots of cups and I just ensure I have all I will need already in those cups or top them up in my car before going into the cleints home.
I would never clean my gun at a clients house either.
When doing a tanning party, I go in to the clients house and hand out the consultaion cards and get the cleints to fill them out while I set up the tent and machine.
When I have set up I check the consult cards over & check who wants what colourwise and then group them together in percents, then if I know there are too many 10% tans for what I already have in my cup I pop out to my car and fill a spare cup with the extra 10% I will need.
I spray from the lowest percent to the highest percent and I swap my cups over carefully between clinets in my tent over a used towel and then I turn the towel over or replace with a fresh towel.
I've never had anyone have any issues with tan residue or anything like that. If my tent is clean and my gun is set correctly (which I check at home before going to any appointment) then there is no reason not to tan on a carpet or anywhere a client asks you too as the spray stays in the tent and on your towels - I say I bring everything needed and take all signs that I have been away with me (including the rubbish lol).