AzViper makes an excellent point about getting general location info, what size of gold? If 90% of area gold is (for example) #12 to #100 mesh. Then at the very least you'll know what size classifiers to consider. Predominant gold size predicates recovery equipment! Always has always will, IMO. Unless maybe you are detecting.
And don't try to hand classify #100 mesh in the field. That sounds like something the government would want you to do, a teaspoon at a time/.
Hand Classifying smaller than about #12 tends to be considerably more time and labor. Running -12 through sluices designed for finer gold should give you decent results to maybe #50??, depending on gold purity, amount /type of heavies and maybe corey shape factor. You will know after a trip or 2 what size most of you gold is.
If you insist on using a larger classifier ~3/8+ put a #12 under it, dump the +12 into a plastic pan /tub then hit it with one of those garret pro pointer type things.
-Goldhog my .02 .See it mentioned a lot, I know hes put some effort into designing those riffles mats. He has yet to make a profile that intrests me though, so to each their own. The guy is motivated, productive, and hes trying a lot of different things. In a way, I think the small scale miner marketplace could use more like him. I see him less as a "1 trick pony" and more like the beginnings of another Angus Mackirk.
-Popanson sluice- You could damm near build one of those at Home Depot/Lowes.