A tip for your plan:
Take 20 oz or 1 liter water bottles and cut the tapered tops off. Fill the bottles with your fish-head mix (leave 1/2 inch of head space), top with a small piece of foil, and put them in the freezer door. Night before your ready to go shrimpin, take a drill and punch 3 or 4 lines of holes in the bottles and put back in freezer. Bring out frozen and put them in the trap frozen, they will slowly melt and disperse. When you pull your trap, dump out, and recycle bottle. No mess!

I use 20 oz bottles, put a fresh open can of fishy catfood in the bottom of the trap and push the bottle down in it a bit. Then I punch holes in another can and put it on top, pinning the stack under the trap lid. If you go with 1 oz bottles, rubber band the foil top to the bottle, otherwise you may have more on your trap then in it. 1 oz will be better for long soaks and 20 oz for quick sets.
Any of the other tips were all good additions also. You could also just add vegetable oil to your mix to thin it. Cheap and will suck up fishy in a hurry. Let it sit a couple hours before bottling.
Oh and don't tell anyone about this...our secret.

When I pull them out, I tell people that they are my super secret "shrimp bombs" and the patents pending.