My two cents says if this skeleton is getting vine treatments anyway, why don't you contemplate different ways of doing that to hide the things that bug you and provide more opportunities for shadow and light and running wires?
Did the vines bind him, blindfold him, strangle him, or impale him? Did he explode because he swallowed a pumpkin seed that grew inside him? Did he become a plant/human hybrid with vines for tongue and fingers?
Well, I'm probably always going to say make a monster vs. make a skeleton (But Trevor was ultra awesome!). Looking back on The Twilight Zone, the most horrifying episodes to me were the ones that blurred the lines between humans/dolls/mannequins - where they could become people, and people could be trapped as one of them. So there's a fear factor in a hybrid.
Although really maybe it comes down to Sculpting vs. Lighting. Which are you in the mood for?
Sometimes I forget the narrative that's in my head isn't just known to everybody.
So, to be clear, back in 2011, I decided all future creatures were going to be
Chimera. Now, I have a massive post on what that means to me over yonder if you care to look.
https://www.halloweenforum.com/threads/monster-mudding-with-unorthodox-the-chimera-tutorial.125072/(funnily enough, if you google "unorthodox chimera" I now dominate the first page of results (granted, mostly pinterest pins, but still) and a good chunk of the image search)
So, Villein is a Chimera first. To boil it down to the very basics, he's centered around a particular feature and being designed specifically FOR the lighting. All Chimera are also constructed beings of various parts...Normally this is a mixture of bone and wood...though weight restrictions on Villein are going to eliminate wood as a possibility.
A long time ago, I decided the Bone Mother (who's coming) was the one animating all these creatures, with the vines pulling bits from the earth.
Both Cropper and Villein are being built around the heart. (which if it goes well, just might become a thing with me to be honest. It's violating one of my rules in the thread above...but with PURPOSE...) Though I should note their backstories are SLIGHTLY different. (yes, they ALL have had backstories)
Cropper:
Cropper.
1. a person or thing that crops.
2. a person who raises a crop.
3. a person who cultivates land for its owner in return for part of the crop; sharecropper.
4. a plant that furnishes a crop.
5. a cloth-shearing machine.
Idioms
6. come a cropper, Informal.
a.to fail; be struck by some misfortune:
The production name for Cropper was Mr Potato Heart. It was always meant to be my take on a zombie...so it was a person who crops made from a plant that furnishes the crop struck by the misfortune of running into the Bone Mother.
Villein...is only slightly different.
As part of the contract with their landlord, they were expected to use some of their time to farm the lord's demesne or provide other services, possibly in addition to a rent of money or goods. Villeins were tied to the land and could not move away without their lord's consent.
There's no reason the contract with the Bone Mother would end at death that I can see.
Anyhow...As someone elsewhere puts it "Adding the traditional Unorthodox Vineyness" to my heart.

So back to the other points...The glowy skull is rather pronounced in the dark...IT MIGHT be able to be covered up with just a fresh paint coat. It's a neat effect on it's own, and if it had been even front and back fo the skull I'd have not worried about it at all. It's one of those who's going to notice but me things.
The chest seam can EASILY be covered by the vines...and it's more of a cosmetic thing for me as a skeleton...one of the first things it would lose is the breast plate...and without lungs the vines certainly don't NEED it.... Yes, it's stupid, but my mind is going to the reality of their being a breastplate on this 12 ft tall zombie animated by imaginary vines... Opening the chest also highlights the heart more...but leaving it is certainly a more mainstream approach for people viewing and if I ever decided to sell.