Wow! What a great idea!! I actually have a love/hate relationship with my woodburner - I tried using it to make my dovetails and succeeded in fusing the ends together.
I wish I could use it for that - the cut and burn method takes forever sometimes!!!
When I do my spikes, I sew them straight up and down, then I slightly cinch them - they still lay mostly flat. I usually use a modified pinwheel bow for my bottom bow on my stacked bows, so I think that helps everything lay a bit flatter.
I think I will try the woodburner trick on my spikes tomorrow!