Normally I'd look at this idea and accuse the OP of over-thinking something that really isn't much of a problem, but somehow this has gotten some traction in my mind.
Make your funnel with a long enough tube that it passes through the barrel and and into the chamber mouth so you don't lose powder through the cylinder/barrel gap; it wouldn't need to extend more than 1/8" into the chamber. My preference would be for the powder to travel down the tube and into the chamber without being disturbed when I withdraw the tube from the chamber. Leave the revolver at half-cock in the stand so you can index it between dumping charges. Dump powder, lift funnel, index cylinder, drop funnel, dump powder, repeat as necessary. This would give you somewhat of a drop tube effect, settling the powder as it's poured, beside not losing grains of powder to the sticky interior of the barrel. Dang. I gotta make one now, just as soon as I find a brass or copper funnel and some copper tubing. 5/16" tubing would charge .36s and .44s without sticking in the barrel.
In fact, now that I'm overthinking it properly.... if the copper tubing is a slip fit on the funnel, it would give you the option of charging revolvers with differing barrel lengths by swapping to a longer or shorter tube. OR..... one longer tube, with some sort of ring on the tube to slide up and down to accommodate for the barrel length. Even a rolled-up rubber band would suffice in that role.Too long a tube might make the whole loading stand prone to tipping.
Great. Lord knows I needed another project.