Where can I hide Rico Delgado's body after killing him as the tattooist?

What I did for this mission was to save Rico Delgado for last, as he has an escape route very nearby. After killing Rico, I deposited his body out of view of the door where guard comes in, then stealth knocked out the guard who came to check in. I then left his body on top of Rico's body, took the car key from Rico and the guard's uniform, then jumped off the balcony and made a break for the garage to escape.

There is also a closet in his wife's dressing room which you can use to dump his body.

Another option is to complete the tattoo without killing him. He checks your work in the mirror, then when he goes to get a drink knock him out and throw him off the balcony. It gets marked as an accidental death and won't wreck your silent assassin status. Then just stroll out of there.