The pattern continues:
Regiment/Brigade - 50,000 tons - next highest officer
3 battalions of 12,500 and the HQ of 12,500 that has engineers, L. Artillery if it isn't an artillery brigade, AA, and supply for everyone below. Consistent with modern RCT/BCT tactics this can now stand mostly on its own as it has pretty much everything necessary to defend or attack with it if you've done a good mix of units at the company level. And it fits in one 50,000 ton commercial transport for moving around and in drop ships for landing on planets.
Division - 250,000 tons - next highest officer.
Now a slight deviation as the unit isn't nearly as specialized a formation. 3 Rgts of whatever front line stuff you want (50,000 each). Plus an artillery Brigade (50,000), engineer battalion (12,500), and an AA battalion (12500).
This allows people of higher rank with good construction, artillery, and AA specialization to still have units to command. This fits in a fleet of 5 transports. The HQ itself stores nothing but bunches of supplies for the other units.
Now if you want to give the even higher officers something to do you can combine these into:
Corps - 850,000 tons - next highest officer
3 x Division (250,000), plus Hvy Art Brigade (50,000), AA Battalion (12500), Engineer Battalion (12,500). The difference goes to the HQ to hold even more supplies.
Finally, if you want, you can have all that united into an Army:
Army - 3,000,000 tons - highest officer
3 x Corps, plus maybe some planetary defense batteries, more supplies, special troops, army level artillery, AA, and Engineers. I don't think an army or a Corps is ever really necessary, finding guys with that high of a combat command rating is hard anyway. But its easy to keep stringing this together if you want.
I don't know if this is helpful but I'm curious what you guys think. I've tried so many different organizational philosophies, even one based on the band of the red hand. I think this is the best for RP and gameplay purposes.