I generally don't like anything protruding from the sides of a plastic, like spider legs. My friends at Culprit make a panfish sized "creature bait with twin twister tails and legs as you suggest. I pull the legs off those baits before I rig them. When these baits were first available I tried them right out of the package and can't say that the performance impressed me. Removing the legs, though, turned that around.
These little fuzzygrub look-alikes have been doing quite qell in certain waters and applications, but like the real deal I see a specific window where they work well. Its worth it to have them along as they don't take up any real room in the tackle satchel and they get used when conditions get right. I think the flash at the hook end of the plastic helps to get fish connected where legs off to the side re-direct their attention to an area of the bait which is away from the hook....just my two cents. I make this statement based on the number of fish I've caught using the legged bugs over the years that were hooked on the outside of the mouth. Clearly the fish hit the bait, but with the hook not getting in the mouth when the set came.....well.
You could trim the crystal shorter I suppose and if it were threaded thru the plastic quite far forward it might mimic external gills like what we see on a mud-puppy. Maribou or a few strnds of bright yarn might be a better option there though.
Try your idea. I don't mean to sound as though it won't work, I just have my own preferences towards plastics. And indeed, sometimes I do miss the boat.