Seen a couple of your other posts but didn't respond until now -- welcome to the forum.
As for the haven... yes, it would be great to change the Santa Monica haven, or even make your own. But the current Bloodlines engine does not allow changes to the maps. That means the blood on Mercurio's floor never gets cleaned up, no new havens, etc. No changes that are not hard-coded into the game.
There's a site called Bloodlines-Resurgence (you can Google it) that is trying to change Bloodlines to a new game engine, that would allow modders to actually change maps, and make entire new maps, for new adventures. Unfortunately, they've been working for a few years, and from what I can tell by their porogress they'll be at it for a couple more years at least. Me - I'm not holding my breath.
Another mod, Bloodlines Antitribu, has posted some interesting game videos at Planet-Vampire.com. It looks like they have changed the maps (at least at the Malk Mansion), which makes me wonder how they did it without breaking something. But that hasn't been released yet, either. Went to their site, but I was unwilling to register just to get info.