Can U imagine it being buffed and supported by Jackson(s)?
That's a lot of popcap next to 3 rifles (most used opening), 2 real echelons, AA HT, maybe AT gun, maybe rangers, ambulance. Pak howi is needed in case of emergency blobs... If you plan to fit Jacksons with the Pershing next to that, good luck. Maybe on some 150 popcap maps.
You don't have to test it, I can tell you that you can have 1 pershing and MAYBE 1 Jackson, depending on what you have lost during the game. I seldom have squad wipes. If they do occur, it's due to some RNG mortar shell or RNG rifle nade from grens (that rifle nade will either wipe a spread out squad or barely damage a clumped up one, it's really RNGish). So if I don't lose anything and I have 3 rifles, officer, 1 or 2 pak howis, AA HT, ambulance, one ranger zook squad.
So that infantry + team weapons + AA HT comes out at 80-90 pop cap with Pershing. So that leaves 10 popcap for JacksonS and ShermanS. Good luck.
True story: I used to team kill my own units sometimes so I could fit a jackson on the field next to the pershing cause the game was getting prolonged and a couple of recon planes spotted massed tigers and panthers. You know that point in a 3v3 game where nobody can really do a push or flank cause it's 3v3 and not 1v1 and there are a sh**ton of units on the field. Well, axis are at an advantage here cause their heavies > usf/brit heavy. If you don't have a soviet player on the team, you really need to end it before the game reaches a point of "fuel is not a problem, pop cap is".
EDIT: the "fuel is no longer a problem" is dangerous vs good axis players. Bad axis players will just run in your units head on, taking the first hits and dying and crying on chat how Tigers and KT are useless and super weak compared to TDs which CAN kill them. A good axis player will mass tanks, have a couple of obers/pgrens, something to repair and blitzkrieg your ass. I've seen people throw their grens/volks, raketen, pak40s, etc. and just let them die. It took me plenty of lost games to realize that they were just opening up the pop cap for more heavies. Now, when the game has reached 40+ minutes, and the enemy is just capping points without any respect the the lives of those men, I know what's about to come. A LOT of times you would kill their expendables, only so that 3-4 minutes later you encounter a Hail Marry of tanks on your flanks/front, everywhere. Now, if axis starts using that old Soviet technique of "Meat Grinder", I just start pushing to their base. Most of the time they are NOT rebuilding the said units but bluffing. That's my own experience.
So no, you won't fit multiple jacksons in an average game, next to the pershing.