I believe most of the exemptions will continue as no government wants to appear to be penalising the disabled.
Without V2G the system is unlikely to work. We could of course install millions of batteries to soak up any excess electricity generated overnight or on particularly sunny days but V2G would appear to be the obvious solution and an essential part of the grid make up.
If we only charge people for using motorways, dual carriageways etc then the surface streets, in many cities, will become choked with cars avoiding any charges.
I think the best way to deal with rural driving is to charge everyone the same amount and then look at people’s post code and give a reduced rate to those genuinely affected.