I've toasted 2-row Pale and it didn't really darken the beer much at all. It was only half a pound and represented only 2.5% of the total grain bill, so I don't think I would have been able to tell any way. Best thing you could do is toast it and then compare it to a couple of other grains to guesstimate the SRM.
Drinking on the keg: BPA, Brown Ale, Dry Mead, Wee Heavy aged on Oak, CAP
Drinking in the Bottle: