When I bought the car in April the guy told me he was using company transport and the Omega had been been garaged for3 months, when he went to start it the battery was flat and is son had to get in through the boot to unlock.
I then parked it up for a month whilst sorting out insurance and ended up getting in the car the same way.
Had issues with a dud battery on my GLS, which is when I started looking into the power connector thing, but on the GLS I have twin trailer sockets and I think the second socket has a permanant live (for powering a fridge etc) so I was going to get annother plug with a couple of leads and claps just to add power for the central locking. But maybe worth considering to add a trickele charger when not in use.
Where I live at the mo I stuffed for chargeing the car, when I move there wont be a problem for that at all, so will be worth a mod of some form. In fact a live connector at the back for trickle charging would be easier.