Rim light for small group

I'm planning to take a formal group shot of my son's Under 8s cricket team (there are 7 of them). It will be outdoors, most likely twilight. I plan to underexpose the background 2 to 3 stops.

I normally just use a 600EX in a sliver reflecting umbrella high right frontal (a few metres to my side) for key light, but am thinking about putting my 430EX behind as rim light, for some separation. I haven't done this before.

Should I use the strobe bare on the ground, directly behind the boys? to the side and out of shot? In a shoot through umbrella, directly behind or at the side? Will it look funny if I pose them in 2 rows (i.e. rim on the kids behind, but not necessarily in front)?

What power ratio would you normally be looking for, between the key and rim?

Anything I haven't thought of?

Thanks in advance.

Not directly on the ground or it will only be visible on the sides of their head, not the crown. Get it up a bit and you can get it to start hitting he tops of their heads.

It probably will look weird to have boys in the back with rim light and from without.

Issue you have with a single light in back and a single line of kids is that the kids at the edge will be getting the rim thicker on the inside of the photo, and very little or none on the outside.

I might go with a rim/hair light on both sides of the group.

Left Handed Brisket wrote in post #18192329
Not directly on the ground or it will only be visible on the sides of their head, not the crown. Get it up a bit and you can get it to start hitting he tops of their heads.

It probably will look weird to have boys in the back with rim light and from without.

Issue you have with a single light in back and a single line of kids is that the kids at the edge will be getting the rim thicker on the inside of the photo, and very little or none on the outside.

I might go with a rim/hair light on both sides of the group.

Thanks for your response.

I only have 2 speedlights, so 2x hair lights is out.

Perhaps I will just aim to use the big old rim light in the sky, if I can get the shots in before sunset.