The setup you suggest doesn't look like an easy / relaxed setup to me. Melee mixed up with ranged spell dps is probably one of the harder combo's. The most straight forward combo is for me pally tank + 4 ele shaman (one dual resto spec). You basically only need 1 spam button to do everything at once (heal, tank, dps).

If you are going 5 box, why not make use of RAF and go for 1 or more new teams? Ualaa has posted very useful info in many of his posts on this board. When you have a prot warrior/pally you can boost a team from 0 to 60 in a day/weekend. If you boost another team from 0 to 30, you can use your first team to grant levels to your 2nd, so you end up with 2 teams at 60.

Just check the sticky threads, there should be a RAF topic which covers this in detail.