I think you can maximize your city garrisons. It looks like you are using full German SEC Divs in many places. Break them into Regts. Many cities only need two SEC Regts, and most usually only need one, which will allow you to use the larger Rum and Hun SEC Bdes for larger cities that need them. You can then free up all those regular combat units (even if they are Allied troops) from garrison duty and send them to the front or use them for digging.
Just from a quick look at your last map, with some careful shuffeling of garrisons, you should be able to easily free up the Hun Mtn Bde in Rovno, Slovak SEC Div in Kirovograd (despite being labeled SEC, this is a unit that has the size and morale to be used at the front until 1943), the It Div in Krivoi Rog, the Slovak Mot Div in Kiev, and the Rum Inf Divs in Kiev, Odessa, and Cherkassy all for front line duties.
Off the top of my head, Rovno, Proskurov, Kishinev, Vinnitsa, Zhitomir, Krivoi Rog, Kirovograd, Cherkassy, and Nikolaev (just to name what I can see on your last map) all can be garrisoned by only one German SEC Regt each.
You will get enough SEC units to cover everything over time. You can temporarily get away with some cities not having 100% garrison. Don't panic. Keep a few Rum Cav Bdes on hand to knock down the partisans until SEC reinforcements arrive.
Another good tip. Too bad I saw it now and not before I did my turn.
This does however leave a question in my mind, what is the button to see garrison "levels" again?
"Hun skal torpederes!" - Birger Eriksen
("She is to be torpedoed!")