Best approach to working with perforce is to work in a user/feature branch then you can avoid checking into the trunk whilst still pushing your changes into the depot.
When creating a branch, you don't have to branch the entire trunk or source branch - you only need to branch the files you're working on - you can map the rest of the files into your branch via your client spec.
TBH - just buy & read 'Practical Perforce', it has heaps of useful info on how to do this and is very much worth the money if you're using perforce on a daily basis.
Another very useful feature of perforce is 'jobs' - often described only for bug tracking - it's much flexible and allows you to store a changelist history attached to a tag so allowing you to create 'metatags' and attach revisions to it i.e 'NightlyBuild' or 'BreakingChanges or whatever you want.
HTH.
