Combinations - Heroin and nitrous oxide

[EyesOfTheWorld]

SWIM and one of his lady friends are planning to indulge in this combo soon. She is an IV user, SWIM insufflates, but they titrate their doages accordingly so they both achieve roughly the same high, usually to the point of a slight nod (ie: nodding off but easily awakened by a tap on the shoulder or calling their name). SWIM is planning to have a friend drop of a 35 pound medical grade nitrous oxide tank at their next session. SWIM was thinking a good idea would be to lower the heroin dose slightly so as just to feel the euphoria and sedation without full on nod, and use balloons sparingly at the peak of euphoria/rushes to intensify. Sexual activity or physical contact (massage, making out, general touching) may be a possibility here. Anyone can advise SWIM on how to make this combo work for he and his friend?