At the end of the day, the size of the base you can build and maintain should be done on a person by person basis. One person does NOT need space to store 20 vehicles, 2 choppers, 12 safes and a million storage sheds. Thats utter ****e.
All bases should be destructible while the player is online, if the player does not login for XX days the base is removed or automatically made destructible. Purely for performance reasons and should be tweaked server by server.
The issue with DayZ is that it is 100% persistent in a world you're supposed to survive. You cannot physically be online 24/7 if you're a normal working/student/family person. You have other commitments, if your job was DayZ then it would work. The map is NOT big enough to accommodate the traffic some servers get but the issue you have is that if you have as server that can house 50 players maximum, chernarus is good for action.. maybe a touch too small.. but if its too big you'll find people condense to areas anyway or they get bored. Its a hard game of balance here.
DayZ is an MMORPG just on a smaller scale (server size) and you should be able to logoff with everything or at least be able to logoff at set times and know when you login you havent been destroyed. When online, you should be entirely vulnerable and it is YOUR responsibility to defend everything you own.
If you want a base, build one you can support. 4 walls with a roof and a locked door is all anyone needs to put a tent in. This is easy to replace with just a few hours of building if its destroyed. Then go out and destroy stuff. If you want a big base, be prepared to have to have the manpower when online to be on stag to defend it or scale down to what you can manage to rebuild.
The issue with Epoch is that everything is done wall by wall, floor by floor and this takes far too much time compared to the time it takes to destroy/maintain it. It also heavily hits server performance.
The Arma engine is not the right engine for this sort of game. This game needs 100's if not 1000's of people per server with an absolutely HUGE map with offline protection with perhaps a hardcore version where your stuff is vulnerable 24/7