Tom,
When I'm solo I use 2 lights, a hand held Stream Light with 3 outputs the low setting is around 50 lm and the high being around 150 or so.
The second is a cheap Coleman headlight that I position over my left eye and when a frog is located and I'm ready to shoot I'll turn it on to make the shot. A little more difficult then having a buddy with you to shine, but it can be done.
I've tried it both ways from a boat and from the banks, and prefer the bank when I'm able to get clear enough shots.
Also I live where we have a couple of WMA and several waterways, I'll Goggle earth the areas and look for dead lakes or with only inlets where frogs like to lay their eggs.
If the edges are too thick me and my buddy will go in on a pre scout and machetes us a path around the banks to get shots off.
Last year by my count we took about 200 prime frogs ranging in length from 10" to 16". Lots of fun and keeps you tuned in at least for shots under 15 yards