The gates for segregation appear to be at each end of the east stand of which only the one between the North/Town stand would be used (obviously, no need to block them off from going into the non-existent south stand!). I'm sure it would be possible - technically - to split the stand itself, but that's not the problem: you can't split the concourse. I thought the rules for segregation are that away fans must have their own snack bars/toilets and given the entire east stand is serviced by one concourse that can't be shared, I would guess we would have to give the entirety of the stand to away fans in games we decided to segregate.
I'm assuming the long term plan is that the south stand will become the new away fan stand.... once it's built. Makes sense as it's the smallest of the lot (at least in terms of capacity - it's the stuff behind it that's going to cost the big bucks to construct).
EDIT - I suppose one solution would be to split the East Stand down the middle(ish) but block off the toilets and snack bars from the Boston fans' side, and have them walk around to use the facilities in the Town End instead. Not sure if that is actually allowed though, under the Green Guide regs? Be interesting to see how they actually do it... surely away fans will be allowed to games? We should be well out of Covid restrictions by then.