I try to mount mine in a manner that will prevent the nosecone from hitting the fin can when it's under canopy. It also depends on how long the shroud lines are.
I once was testing a zipperless design and managed to blow the recovery bay off the fincan, but the parachute didn't extract. Now I make sure that the mounting point for zipperless deployments is far enough back to ensure that the chute will come out upon separation.
Also important to note, make sure that your nosecone is securely attached to the recovery bay when using a zipperless design. My Cherokee D PSII 2.5" upscale nearly impacted the ground when the nosecone and the bay separated. The chute got stuck in the bay. I got lucky though, at the last possible moment, it extracted and deployed. Unfortunately, my camera's battery chose that exact moment to die.
[video=youtube;3qrm-fAsqLI]https://www.youtube.com/watch?v=3qrm-fAsqLI[/video]
My next comment was "YAY!!! I meant to do that!!!", but honestly I was quite embarrassed by the close call.