The heating elements I used went inside the barrels. The barrels never got too hot to touch, but you certainly wouldn't want to hold on to them all day either. If the ribs are marginal enough to have come loose in the set-up I was using I would welcome it - that would mean they needed relayed to begin with. I'd rather find that out in the shop than in the field.
You could make a set controlled by a rheostat (sp?) and play around with the settings so that when you wipe some water on the outside it evapoates quickly. If it evaporates from the outside it will evaporate from the inside.
