Your solid tire solution sounds like over-kill to me. I'm guessing that your blowouts were caused either by a faulty rim tape install or by tubes that were too small for your tires. A ballon will burst if it is over expanded.

I used to get blowouts all the time until I took the trouble to address those very same issues on my cargo bike; since then I have not had a single flat, though I have worn out many sets of tires.

Anyway I hope you get the problem solved and finally get to enjoy your electric.