If you start with T1, you need AT nades or you'll be obliterated by AC if you want to play without guards.
If you start with T2, you need molos for clearing buildings as you obviously won't have flamer M3.
And no, AT guns can't easily deal with P4s, not without numbers, not without AT nades snaring them for their 50% longer then PaK reload to give effect and without guards to hold it in place.
Its not even theorycrafting here, its plain logic if you have any idea on how sov units work(which in your case might be a questionable ability).
You only need 40 fuel to get the other tier . that's 4 min into the game. sometime people have not even engaged the opponent on larger maps. if he goes tier 2 and buy even one vehicle then its already pretty much even. Its a small delay to get my t-34 out but this gains me great benefits early and late game. as i generally use a combination of maxims penals and guards.