Rim tape

I used electrical tape and the tube pressure went through it like a hole punch after a few weeks. Went to using a strip of old inner tube after that which worked fine

Sounds a bit backward to me. Inner tubes are stretchy and flexible, the very reason why your ACTUAL inflated tube needs a rim tape to protect it in the first place. PVC tape is pretty tough and not stretchy a couple of layers does a great job. You can see if it might have been stretching around each spoke hole, just add more as necessary.