Feels like a lot more effort should go into this then just tossing in some Halloween assets and building a quick Hell dimension. Folks nowadays only tolerate Halloween reskins if they properly transform the map into something new.
Compare Mountainlab to Mann Manor, for example. The layout is the same, and yet it feels like an entirely different map. Likewise, Bonelands should be a completely different environment.


Let's see... if I was re-skinning this map using assets already in the game, here's what I'd do:

1. Make the team's spawns into old castles, repurposed at some point into asylums/prisons. I'd achieve this by mixing medieval/Halloween assets and textures with props from maps like Enclosure, which includes things like checkpoint towers, electric fences, and observation windows.

2. Make the central point a stone or concrete bridge, and the pit beneath it a mist-filled dumping ground for bodies. You could even add a layer of bones beneath the bridge using Zues's TF2 bonepile texture (you can find it on Youtube). Now the name "bonelands" makes sense!

3. Have the buildings on either side of the bridge be old prison checkpoints, again using Enclosure and Yeti Park assets to get this effect.


That's just my own take, of course. As for Halloween gimmicks, I'd have either skeletons emerge from the pit when the point is captured, or have a huge hell portal appear under the bridge, accessible by anyone who jumps off, into the mass grave.