Has anyone used bubble wrap around a receiver and then crashed. If so, did it hold up and protect the receiver? I am tempted to use it, the material comes in a lot of my shipments and might be a good replacement for foam, but I sure don't want it to collapse in a crash. What do you think?

Years ago when I was flying sailplanes I used bubble wrap and foam around my receivers. Some hobby company was marketing packages of the combination for that purpose. One day I caught a beautiful thermal and soared to a very high altitude. Later I found that all the bubbles had popped! I don't know exactly what altitude would be the limit for this material and the stuff survived other flights that did not get so high.

It's probably not a problem for most sport flying but something to keep in mind if you fly anything that can ride a thermal.

from first hand experience, yes.
two layers for batterys. saved my electrics.
also wrap my ignition box for gasser when its in the cowl with the foil version to help repel heat. found in the insulation dept. at the hardware store, had some scraps left over from insulating air ducts in my attic.