When I did the Rhino slaying, I used a Mage/Druid and 3x Shamans. The Mage would run around and Arcane Explosion for quite a while, I think one of the shammies did Earth Shield on the mage too.

Then have the totems slaughter a lot of the rhinos at once.

Was not much of an issue in having the lowbies need to hit mobs quickly, as the killing totems were not dropped until I had gathered a bunch of the mobs up.

Incidentally, it was the quickest I've ever burnt through full rested with toons, 1.5 levels of rested in just under 20 minutes. I initially gathered a lot of the rhino meat, and had my auction toon (via Quick Auctions) keep 5 stacks of meat (whatever number the cooking daily requires) up at all times. I sold the meat for 1g each, and it took several months to sell it all.