it is possible if your tank is a hunter, otherwise your healer would oom from all of the damage your tank would be taking
What if the whole group was made of pallys? 1 Prot, 1 holy, and 3 rets, or something like that. They could all pitch in to heal when need be... you just have to remember to stagger the heal macros on your different toons.
Twinko has pleanty of healing classes in his sig, I think some combination similar to what I mentioned could work.