Hey Semperfi, I've been looking at your ideas and want to tell you that you're doing some amazing work. When it comes to gameplay and quality of life changes your additions and changes pretty much hit the nail right on the head.  If you're interested I've got some story-based suggestions for you're mod. Now I know these suggestions could be a lot of work to implement but it would really add a lot to make this mod even more perfect. Well here they are:

Weapons:
Could you add the Arisake to Der Riese as well? It was originally planned to be in Der Riese and they even had an upgraded version finished called ''The Eviscerator'' but they scraped it last minute. it would have performed exactly like the upgraded Kar98k.

Perks: Now I know you want to change Double-tap to make it so it does 1.5x damage because you don't want to make it OP. I personally disagree. I believe you should just make it like Double Tap 2.0. and make the perk do 2x damage for all bullet-based weapons. The reason I say this is that most weapons after round 20 are completely useless in the original version. Not to mention the fact that you could only choose 4 perks so it's not like this is gonna affect perk variety. This will make the weapons of WaW a bit more comparable to BO2 and after when it comes to performance and it will encourage players more to try out some different weapons.

Verrückt:
Could you maybe switch one of the marines with Dempsey? That would be awesome since Dempsey, John ''banana'', ''Smokey'' and Paxton ''Gunner'' Ridge went to Verrückt to rescue Peter McCain. However, they were too late. He was already gone (to Shi no Numa) and Dempsey was the only survivor and was captured by group 935.  This would have to be sane Dempsey though since he wasn't experimented on yet by Richtofen. Maybe you could use the WaW Dempsey's player model but paired with one of Primis Dempsey's voice packs (from origins for example). however, I would take out all the voice lines that contained anything about future maps.  

Shi No Numa:
- Could you maybe add the howls of the Hellhounds sound when the round begins? Probably no one knows this but the Hellhounds round start sound originally contained a terrifying howl sound. However, this was only on the PS3 version of the game funnily enough. Here is a link to an old video if you wanna watch it: https://www.youtube.com/watch?v=cPLkkKVDfXs It would be so dope if you could add this sound and maybe to Der Riese as well.  
- Could you maybe add an easter egg quest to the map? Nothing too crazy. Maybe you could add a teleporter to the map somewhere with a buyable ending which you can buy after you find Richtofen's diary in the Doctor'squarters. This would be amazing since it was with a teleporter that they got to Der Riese. This is proven by the timeline and the Der Riese music video.

Der Riese:
Could you maybe also add an easter egg quest to the map? Again, nothing too crazy. Here is a short overview of what happened on Der Riese for some inspiration: The Ultimis crew returns to the Der Riese facility from the Rising Sun facility on October 28th 1945. With his diary, Richtofen plans to use the teleporter to return to the moon and confront Samantha, a little girl who is in the M.P.D., who Richtofen knew from his past. Upon arriving, they must face limitless hordes of the undead as they continue their journey. Unfortunately, the Wunderwaffe DG-2 overloads the teleporter and changes the intended location to Kino Der Toten, and sends them through time as well — causing Richtofen to drop his diary which is later found by Soviet forces when they enter Der Riese to steal all of Group 935's technology and research.

Bonus:
Could you maybe add some more swastika flags on Der Riese and especially Nacht Der Untoten and Verrückt to really add to that Nazi Zombies vibe that Kino Der Toten does so well. Maybe add some Japanese flags to Shi no Numa as well since it was a Japanese research facility. Just some extra Ideas.

I hope you find these ideas interesting and enjoyed reading them. By the way, if you need any help with Co-op testing then hit me up. I'll gladly help.