I've been using this technique as a replacement for Lawena for a while now.
https://www.youtube.com/watch?v=lH4scK3uB_s

It's completely vanilla, more robust, and works with either version of the game.
Only problem is it can be tedious to set up. This would be greatly automated by a launcher.

I would also love options to download HLAE, FFmpeg, CastingEssentials, SparklyFX, etc.

I've been dying for a new launcher that removes all the intimidating setup and downloads for newbies.
If you make a git repository then I will gladly make contributions!

HLAE still works somewhat for 32-bit, but you must launch tf.exe and NOT tf_win64.exe.
Features like AGR will be stable again after my patches are accepted and released:
https://github.com/advancedfx/advancedfx/pull/929

(The latest patch is now released, and should fix all known issues)
A 64-bit port will likely never happen, or it will take a very long time.

I think it could be easy, but only for entities. (Player ragdolls aren't entities, but idk about dropped weapons). I would just check its parent entity.

It would be annoying to configure though. Do you want it different per-class or per-player? How do you select all possible colors to avoid clashing (especially in compressed lossy video)? It seems niche enough to require a more generalized and configurable GUI. Logic nodes or scripting would make it more complicated but provides the greatest control.

I suggest you create a feature request by opening an issue on the GitHub or discussing it in the Discord.

This is at the engine-level. It is very similar to HLAE, in that it has streams and FFMpeg support. You can get proper depth data and create mattes. It can create as many composites of a single frame as you like.

Sparkly FX is an open-source TF2 video recording tool made by yours truly, now in 64-bits!
The 64-bit port was done in 1 hour and is mostly stable with few bugs.

Website: https://github.com/cademtz/sparkly-fx
Downloads: https://github.com/cademtz/sparkly-fx/releases

Features:

• Record various image and video formats with/without FFmpeg (mp4, avi, ...)
  
• Faster-than-realtime recording with multi-threading and hardware-acceleration
  
• Output multiple streams/layers
  
• Highly customizeable streams (Multiple mattes, visibility filters, color adjustment, unlimited FOV, depth)

Usage:

• From the releases page, download sparkly-fx.zip and extract all contents
  
• Using a DLL-loader/DLL-injector (See: HLAE loader), load the extracted 64-bit DLL file into Team Fortress 2.
  
• In-game, press the F11 or Insert key to open and use the Sparkly FX menu. (A console message from Sparkly FX will appear if it loaded correctly.)

Source code and further details are available on the website.

Images:

https://i.imgur.com/ALCmcwC.png

https://i.imgur.com/ISQ71lk.png

Now this, is epic