TMI: Lesbian sex positions and protection

Scoobie
So one of my best friends came out as gay and we got talking about how she likes to get down.. she said she loves to scissor her bae but was concerned about STIs. I foolishly said you can use a dental dam but immediately thought how would it stay on in the throes of passion? So any ideas what a sti conscious sexual gymnast girl can use to stay safe? Thanks !