Proposition:
Standardize ALL mounted recon platoons at 10 x vehicles.

IBCT Recon SQDN mounted troops utilize HMMWVs.

SBCT RSTA SQDN uses 1 x M1127 troop (3 x 10) plus 2 x HMMWV troops.

SBCT IN BN uses 1 x M1127 platoon.

HBCT ARS (not really an ARS anymore, but anyway) uses 3 x M1127 troops (3 x 10).

HBCT CAB uses 1 x M3 platoon.

Alternatively, we can go back to the mixed troops from the ACR, LCR and DIV CAV- each recon troop has 2 x recon PLTs (10 vehicles now, instead of 6) and 2 platoons of tanks/MGS/TOW HMMWV. The organization of all troops (and platoons) is the same. The difference is the system.

Rough math (I'm sure TAH will correct me) tells me that we can get the force structure personnel (not sure about the systems, but that should be doable, too) from the overhead (HHCs, CO HQs) of the HBCTs we have to reduce to put 3 CABs in each HBCT, with requisite CS/CSS elements (FA Btrys, EN PLTs, FSCs, etc).