Here's what I did, simply because I wanted to get mounts on as many as possible on the new team.

I used an existing account with some L70s on it to refer a first one, activated it, and then chained more RAF's. In addition to getting more mounts for the multibox team, there are some nice summoning options too. (You can have each person summon the next one in the chain and warp a whole team to where one of your fast, mounted L70s on the veteran account is.

Vet Acct 1: L70 Mage powerleveler, "Hunter0", L38 Priest (will join them post SM powerleveling) -> RAF1
RAF1: "Hunter1" -> RAF2
RAF2: "Hunter2" -> RAF3
RAF3: "Hunter3" -> RAF4
RAF4: "Hunter4" -> RAF5
RAF5 - Nobody, just activated it in order to get mount for Hunter4.

I used game cards so that the mounts are instantly available, instead of having to wait for the two months of subscription. I'll eventually character transfer off Hunter1-4 onto my existing shaman multiboxing accounts...

If you set it up this way, you will get 300% RAF XP on everyone as long as you're not playing a L70 character in slot 1. When I'm powerleveling with the mage, only Hunters 2-3-4 get RAF bonus XP. It's not much of a problem, since Hunter2 can just gift the levels to Hunter1 to make up for the loss. They're all pretty well synced up with maybe half a level difference in XP at L36. When the priest is in control, everyone gets normal RAF bonus, and I'll switch to priest + 4xHunters at L40. Then, I can gift Hunter1's levels to the "Hunter0" character, if I really want to.

Anyhow, hope that helps.