You could use ther same type of fitting that is used on Locos and traction engines to tell what level the boiler is at, most of the ME suppliers will have water gauges.
They are not hard to make and you could use perspex/acrylic tube rather than glass
Another alternative would be to cut a slot in the side of the tank and cover with a sheet of perspex and cover plate with matching slot secure with some self tappers or nuts and bolts. bit of sealant or gaskets between and away you go. I think JS posted something similar recently, can't find the text but the photos should do.


J
Edited By JasonB on 21/04/2014 13:22:03