You will have to redesign OKW if you do anything with the shrecks on volks. Because the raketen is almost useless against flamer tanks or anything that manages to get on its side and isn't as slow as an IS-2. Well, at least it can retreat and be put into buildings with the downside of having no shield to give heavy cover to its crew
Sadly, I don't think there will be any other changes to OKW design other than giving the p4 to the flak truck
that's just it, there are a lot of complaints against it but by current faction design it is a needed crutch. sure you can hope that alayer of raktens and mines will work but thats a big if. The current presence of flame tanks (looking at you crocodile) makes the old ides obsolete (ideas of nerfs ppl had) this is really compounded by combined allied arms. two (or even one) crocodile backed up by some jacksons or other at can cause a flat out retreat or some losses. if you have ost and some caches not a huge deal but if strapped for resources its that snowball effect.