The way I'd handle it would be to emulate the values in trytes simply as numbers with an artificial cap on them. The only time the actual trits would have to be simulated would be for tritwise operations.
Log off mechanics have already been discussed although no real decision has been made.
I suspect that for most servers the number of vcpus owned by the players will be low. Last discussion I was in would probably put this into the realm of 6-10 vcpus per player max, spread over one to two ships and a base/station. I suspect that most vcpus will be running on npc ships.