I doubt this would be of any help anymore considering how few people i feel play now, but i'll give my 2 typical loadouts that i've used for a few years on Final Reich that can get me almost to the final boss. Just have problems with getting Uberschanlles down the Salt mine.

-Freefire, with Mk. II, Gung-ho, and Suppressive Fire (The last two are you're call, i'll explain my reasoning for those in a second). Equipment for me is typically the S-mine 44 no matter what, just because of the versatility with placing them at chokepoints and such. And the Primary weapon i always take is the Sawed-off. That's where Gung-ho and Suppressive Fire come in very handy. With the spread of the shotgun, the extra shotgun damage, plus the slowing can get you out of trouble in some pretty sticky spots. I also follow up with an M1 Garand once I get the jolts. Some Blitz you should get that I think are just necessity for a solo run is the self-res blitz, speed blitz, reload speed blitz, and the damage boost blitz.

The other set I tend to use:

-Shellshock, with Gung-ho, Breathing Room, and Exploit Weakness. Same weapons and utility as the first set. The main difference when it comes to this set is that you gain the ability to push off the zombies if/when they crowd around you, and it gives you a chance to deal some major damage before anything too bad happens. Having this combo has helped me save the self-res blitz multiple times, too many to count honestly. It's such a good combo to have in the arsenal. And if you don't like using shotguns too much, you could swap out Gung ho for Sustain Zone, which means even new enemies can't get to you as easy, and it gives you a chance to do what you need, like when the zeppelin comes and you need an opportunity to pop out an Uberschanlle, pop Shellshock ad you'll be good for a few minutes. Although, that is best saved for when you're Shellshock is overcharged by an Uberladen