Okay finally! Firstly, it's so easy to underestimate how intense Standard actually can be before going for S ranks. Hm, I am not exactly sure what this post will be aha but I really wanna share (feel free to ask stuff if you are going for the same - might be able to help :)).
I did every mission in commander mode except for Buy Cheap, Buy Twice and Rust Belt, which I did with two friends. My setup was heavy armor, 9-bangs, beanbag rifle and no secondary (no ammo at least) on everyone - then one ram, a few wedges and one mirrorgun on each team (blue and red).
Using both the teams dynamically was quite tricky for me initially (playing on Xbox), so what worked wonders was having one of the teams Fall in while commanding the other (this keeps you safe while also keeping oversight of everyone). After a while it gets easier and easier to reliably push with both - but would definitely recommend this approach if not super comfortable with the commanding :)
The missions that gave me the most trouble were Relapse, Greased Palms and surprisingly, Rust Belt. I recommend running the m320 (I believe?) flash launcher as your tactical - gives you some clutch response capabilities.