Well i'm one for one so far following this on Langres. Didn't even get to the second Ober. As soon as I wiped an early Assault Engie I knew I only had to tighten the noose.
Just keep in mind that you want to drag on games forever with okw, if you are behind just focus on holding one part of the map, don't make an A-move blob,keep your units together but well spread so that stuff like B4s,Scots,120mm Mortars and other stuff won't kill more than one squad if the hits well.
And generally, play very safe, the panther is strong but very expensive, losing it in a stupid way can mean game over if your opponent exploits the opportunity, in other words, use it at max range, maybe barely overextend it and try to rack up Vet, this goes for all of your units, of course, sometimes you'll just be unlucky and a tank or arty piece will one shot your infantry, in that case just replace them.
A small edit:
I usually play with either the special Ops or defensive doc, sometimes the luftwaffe one, basically, the pak43 is a game winner when your opponent is trying to overwhelm you with tanks but has no arty to one shot the pak, (T34/85s/Easy 8s), that way you can place an extremely defensive pak43 near your T4 and use your panther has a bait for the tanks, if he rushes your panther and you are withing the range of the pak43 and a couple of volks with shrecks you'll be able to deal with any amount of tanks.
Otherwise, spec ops is great on urban maps for cheap nades for anti garrison and the 420-no scope STGs destroy all infantry at mid-close range, great for countering shock troops, the command panther also offers great buffs, though it's kind hard to get more than 1 vehile as okw outside of panther > kt.
The luftwaffe one is quite obvious, if somehow you lost your T4, fallschirmjägers are a great replacement for obers, and with some luck you can spawn them to kill soviet snipers.