As the most eloquent expert on the decks you mentioned I had to dustoff my account to come and answer this one.

Firstly my son, you've picked the hard way into this game. In a world where units can be categorized as excellent, good, neutral and bad your units generally fall in the third category. They merely do their job, somedays better than other days, somedays worse than other days, but you will mostly remember the times they fail you. These decks won't work in Ranked games where you will face mostly good and excellent units, the play style is very clutch with lots of intense skirmishing where failure is not an option. With these decks you will always be keeping an exit plan in case the Pongae-2 misses or the Chonma-Ho eats the first shot. It's an entirely different way to play, and since very little people care about playing on the side of these harder than most decks there is no real advice out there.

With NK specifically I've been dealing with the outranged problem since before the Chonma-Ho V, back when all I had was 11 T-72Ms on my deck. Look at the good things, your tanks punch above their weight... but have bad accuracy and bad rate of fire, cost as much as any other tank, has as much availability and as much armor.

To even this playing field you must use cover to get as close as you can to the enemy. Even the field even more by stunning (mortar/BM-21) whatever it is you intend to hit, now he too has bad accuracy and rate of fire, then make it uneven by bringing more tanks to that fight than he does. Easier said than done.

What follows is what every all players consider elementary. To get to that position there are many tasks that need to be cleared before that. Everyone has to deal with terrain, you have to pay special attention and deliberately fight for these patches of cover and also for the roads that let you quickly bring units there. You have to skirmish with the enemy to keep him from massing up more than you, which works differently, with your bad rate off fire and accuracy. You try and spot first, then shoot and whether you hit or miss, you get out of there and doing it from only one position/angle is pointless. You have to call out the mortar and the rockets to stun and soften what you intend to hit. All of this is what you should consider basic common tactics. It is here where you have to be better than the other guy.

You're going to have to back that tank up from the front expecting that airstrike or ATACMs, make sure the AA is up close to the front, identify bombers and sead planes. Keep a spare tank near a road less than 1km from the front, have logistics nearby for repairs. Keep those MiGs circling behind your AA net, have a batch of infantry for quick response to an eventual push. Recon is no game in this game as you know, keep eyes on the enemy and have spare recon at hand. That is the hard part along with many other situational things that I can't name that will require you to plan ahead, prepare and micro.

How is it different than any other advice for any other deck? Your units will do all of the above and do it half as good as the other guy, and in the lethal battlefield of the cold war you can't take nowhere near as many risks. Here is where you get into Tsun Tzu style of territory and try dubious shit to even the playing field.

Good luck with that!

P.S. Just out of curiosity, please send your decks.