So maybe:
Me: Hey man, I've never been here before, have you? I'd like to play it safe and start to come back when I have about 1500psi.. get close to the line. Maybe start heading up wiht 800psi. How's that sound?
Instabuddy: Uh, ok. That's really conservative.
Me: Yea, but Im just getting used to this gear and I don't want any problems.
Instabuddy: Yea, ok.
Maybe it works out, maybe not. But by making it seem as though you are concerned about safety (and not preaching) maybe he'll go along. Maybe it'll get them thinking at least.