but I'd very much like
to fit nav lights at least, so some sort of shoreside charging system would
be good. I'd rather think ahead and install a 12V system that's capable of
running some other kit further down the line (a depth sounder springs to
mind, and maybe a fixed VHF).

Fitting nav lights and a single 12v battery, such as a smaller group 24 will be
easy. You could also go with a larger grp. 27 and a small guest charger
hardwired in, so you just plug her in at day's end.
We have a laptop with DVD, but have been using the TV instead. The laptop
actually has a bigger screen and uses less power, but the tube set is easier to
use overall.

RB