EDIT: stupid double post. Server seems to have some troubles tonight.
OK, well, the original spell is 1 mile/caster level (of the leader, I guess) for "gathering power," but that seems to assume the tabernacle of the ram is involved. So maybe something like long range for gathering power and close range for drawing power?
That works for me.
And I think I'd go with 1 mile/level for the Tabernacle of the Ram (as in the original spell), and the caster only needs to be present and concentrating to change how the power is drawn off. So, if they are powering Occultation, they can just get it started and then leave.
That looks fine for the spell, although maybe we need to note specifically that only the "head" has to concentrate to maintain the spell.
See, I'd like the Tabernacle of the Ram to be powerful enough to "concentrate for itself." If it takes something elaborate to set that up, it's ok, but I think it should run things automatically.