Shrouding is the only way I know to get them to cast lower level buffs, and it's a bit of pain, as you need to get some money to bring them up, so more than just running to the shroud keeper. And of course this won't work, in the field, unless you are a gating class, and bind at the camp, transport to PoK, shroud down use a gate potion, rebuff, then return to shroud keeper, unshroud, gate back again. Or just stay shrouded at the camp with them.
Either way, getting a 3+ hr Temp vs. a 90min one, from a real player seems a lot easier, unless you play during slow times, where getting a temp may take some time.
Yther Ore.