Seems like you've covered quite a few options and noted many of the cons with each. A couple of other possibilities I can think of would be to set up a small LED light or two near the prop which might help highlight it. A single LED would likely run for days on a couple AA batteries and provide a bit of 'spot' lighting or you could tie it into a small low-volt transformer for extended use. You might also consider lighting with either UV blacklight LEDs, or other blacklights around the scene, then possibly using a bit of phosphorescent paint for eyes. That would likely 'pop' a lot more than simple GITD paint or beads. One other thought - if you can find small 'uranium glass' beads - those give an eerie green glow under blacklight, so might be another option, especially if looking for more of a 3D effect.