I'm finding it hard to comprehend why you would want it bareback without wanting him to cum inside you? Isn't that the whole point of bareback? Personally I'd suggest using a condom to start with until you've built up some trust between you. If he's a 'player' then generally he will have buggered off after a few weeks anyway. Once you have built up that trust then lose the condoms. Easy.
I have to admit the best sex I've ever had are the occasions when I have made up my mind that I want it bareback, let him start with a condom and then remove it half way through. It always blows their minds (and their balls
) It's worth the wait and reduces the worry.