There is no way a pump will run 100% dry unless you have it plumbed to suck right off the bottom. I have run may pumps down to the point where they don't pump water and I have never had one catch fire. Just not going to happen IMO
You should be topping off every day so it should not reach the point of running that low.
Im not 100% sure what you mean by my sump will run dry before the tank overflows.??
Your tank and sump work together and the flow from the tank should match the flow from the sump back to the tank. If this does not match then you need to work this out before you move on..
When water evaporates the level in the tank should stay the same, the level in the sump will drop. Do you have something else going on??