[Wil]

You can set time with command blocks. If you hook one up to a repeater, you could keep set the time to the same time. This would, of course, cause the sky to keep flicking back and forth, but you could hang a lampshade on that. Alternatively, keep it set to midday, when the sun hangs at absolute up for a minute or two.

EDIT: Is there a rough idea of when the adventure will be? If you want a couple of Tools to record and upload the whole affair, we'd love to be there to see the server off.