I tend to agree that "claiming" is going to be the dangerous route. I think it's fine to constantly RP in one place, people may even decide to leave that area to your group, but it could also cause some bitterness if others want to use that area as well. It's my recommendation that area be thought of as first-come-first-served per RP session. If you've RP'd in the same spot for a week straight and no one was there, awesome, but on the 8th night you show up and someone is there, leave the place to them. If you roll up and try and kick another RPer out of a location, you're not really any better than a griefer. If you feel you must claim an HQ that way, I ALSO recommend not using the ACTUAL area IC. Think of it as an instance of the area with a different name and location.
It is important to not, I think, that (as others have mentioned) some good RP COULD come of a scenario like this. If you plan on approaching it as such, though, I suggest to ask in OOC tells first. "Hey, we RP here a lot and thought it would be fun to challenge your group for the area," covers a lot of bases if the group doesn't want to be bothered. And if they DON'T mind being bothered, you've just made some new friends :>.
It is important to not, I think, that (as others have mentioned) some good RP COULD come of a scenario like this. If you plan on approaching it as such, though, I suggest to ask in OOC tells first. "Hey, we RP here a lot and thought it would be fun to challenge your group for the area," covers a lot of bases if the group doesn't want to be bothered. And if they DON'T mind being bothered, you've just made some new friends :>.