You will need some way to mark lost bases as FoG;R bases would be 60x30 for these guys - otherwise they will be just fine. Your unit in the picture would be 6 FoG;R bases.
Nik Gaukroger
"Never ask a man if he comes from Yorkshire. If he does, he will tell you.
If he does not, why humiliate him?" - Canon Sydney Smith
A couple ways to not worry about it is
1: make a couple 60x30mm base with a few guys to make "change" when a unit loses a stand.
2: casualty caps.
I use make up some 60x30mm bases with some dead guys on it so your unit would still have that very cool look you have done.
15mm: Swiss, Spartans, Late Republic Romans, EIR Romans, and can you believe it Samurai. 800 points
28mm: Late Republic Romans 650 points
28mm: Samurai 800 points