bathroom?

[macmanmatty]

I'm building my professional studio (i'm a musician) underneath a rundown 1600 sq ft (80 ft x 20ft) beach shack that is 10 ft in the air . The beach shack used be an army barracks during world war 2 and we had it moved here raised in the air and now live in it !! My question what would be the best way to add a toilet since I'd rather not have clients use the one in the shack and know that no toilet = less clients. Also I'm no near any other commercial bathrooms. I'm come up with various ideas but connecting the bottom toilet to the septic tank at slab level bottom seems impossible or at the very best VERY VERY expensive due to the fact that it is a 10 ft drop to the toilet up stairs. I came up with idea of raising the bottom toilet bathroom floor up three 3ft to get a much better head height on it and use stairs to enter it but that is beginning to look like comical and stupid idea. Are there any other kinds of toilets that I don't have to connect to septic or sewer which we obviously don't have/ and will still look some-what professional and also not very expensive (under 1,000 USD)? I'd let them use the shacks toilet over a porta-john / porta-san.