OK, quick review of my resources reveals a few...
There are two modern towers in the Kalmbach book "Trackside Structures...", and one can easily be backdated by "un-abandoning" the abandoned sandhouse, and adding the (demolished?) sand bunker.
The other really cool one is from RMC Jun-Sep 1988. It is a combined sand house/ coal tower, with the elevated sanding tank attached to the side of the coal tower.
I know I have at least one more plan if either of these are not suitable...
Andrew