The "issue" is the 2x invasion sets per day-- this isn't a permanent feature, it was left in for the Ho-Ri "event" though (generally just one set of invasions per day).

My commander level is 50 now, my Super Pershing is 38, all my remaining 4*s in my main army are 45-46, and all the other 5*'s are somewhere a bit behind Sarah.

I'm able to do the invasions just fine though-- usually I can get at least 3 of them before I lose enough tanks to stop, then I come back to them a couple hours later (after repair times) and finish it. This leaves me with enough oil (heavily abusing scouting, and I do not have the last oil rig yet) to do *either* the PoC *or* some main maps. Now that PoC is an every-other-day thing it means one day I do the PoC, the off day I do some maps.

My suggestion would be (if you're struggling with it), just cut down how many of the invasions you do. Save yourself oil for other things if you'd like to work on them, and especially try to do a bunch of White North runs just for exp farming (I did that for a while before the first event landed, I needed exp badly to even try Ocica).