The old safehouse is trash IMO, why not make it so it gets raided by SWAT or FBI or w/e. But the thing is when its get raided you have to get all your offshore money to a van/helicopter or whatever to get it to escape within a certain amount of time. This should be voluntary though. Then with a new safehouse they could have safehouse customization people have been wanting, then with the offshore money you saved you could use it to add stuff to your safehouse, maybe like gunracks that can give you more weapon slots or mask holders.
This way if you don't get all your offshore you cant buy every safehouse addition instantly, and this could work because only you can be in the safehouse and nobody else can.