Thanks for the response Ray.
Not an inductive load, actually planning to use your board to drive a bunch of garden lights! Already have your V1.1 Pi board looking after the garden watering, was looking at a method for simply turning the garden lights on at dusk, and off again at midnight (and maybe some other fancy bits), and just could not go past a V1 Pi with a V1 opensprinkler board! All is run by solar and a storage battery, the opensprinkler Pi will sit in a box out in the garden, and can then control all things garden lighting! So using FETs will be that bit more efficient than relays.
So given no drop in part (was hoping that you had heard of an obscure transistor that would suit!), I think the easiest solution will be to use a SOT223 MOSFET (a BSP100), but install it upside down – is not super elegant, but it should work.
What do you think?