We're using Tahlia, Ispher, Nara the Fang and I think Eliam (the last one I can't be sure). Yes, we definitely have a shortage of ranged attacks which we have realized is not helping with the exploding skellies situation. Someone from our group want to verify that last hero?

Well, i dont think i need to house rule anything, i could just choose not to explode them as much. Not that I have upgraded them to silver, I blow them up a bit less, and of course once the campaign goes silver, I will upgrade my Eldritch units to gold and one red die of damage will not outweigh the ranged damage they can do while alive....errrr....dead....ummm, uh....undead.....

Maybe the heroes just need the Tomb of Ice expansion so I stop stomping them into the dirt so hard?

Assuming you're still in copper, and SoB runs anything like RtL, stomped heroes is the expected outcome right now. As the campaign progresses they'll start doing much better (again, assuming a correlation between how SoB and RtL play).