If you are on federal property they have a fair bit of latitude with what they can get away with.
When it comes to your home and person-See 4th ammendment rights on Norml website. And learn-verbatum the statements you should make to them in a calm, articulate manner. With a warrant or by waiving your 4th ammendment rights (consenting to search) they can check your ass........and anywhere else they want.
Although a warrant should detail what, where and why they are searching and the pc to support it. If not, or if the search is expanded outside the parameters of the warrant you should again exercise your 4th ammendment right.
i.e If the warrant says home and person then you can deny them access to your vehicle, boat, second home, etc. Most of the time they will have that covered since they will know what you own, where you go and any other homes or apartments you maintain for legitimate or illigitimate purposes.
Good luck, if the feds want you they are going to get you....just look at Tommy Chong.