[Refplace]

I have worked out several ways to handle Astral travel for my Shamans (using Powers) and while I do not use Jumper I think it still fits what your trying to do.
Jumper with limitations like Projection is good for Astral and Dream Travel where you do not physically go.
Jumper with an anchor or accessability limitation for portals covers your crossroads situations where you can physically travel between realms t certain locations.
You can tweak other enhancements and limitations for other situations.
You can use alternative limitations or alternate abilities to cover multiple jumpers. So everyone has Jumper (Projection) for Dream travel and Jumper (Portal only) for crossroads. Bought as AA on the sheet but listed as a feature for no points or dedicated and assigned points.

Those who can do more either buy additional Jumper powers as AA or if you want o assess a UB like cost they have to buy the base power if they can modify it. then they can add variations.