I would use a single flash gun, ttl cabled, a stofen or similar and some cto gel (visit lee lighting for an offcut, or get a swatchbook or a single cut sheet off ebay etc)
This will at least get your flash CT to match the ambient light CT.
Add a diffuser gel, or stofen.
I would set the camera to manual and expose so that your ambient exposure is at -1&1/2 to -1. This means that your exposure without flash will be slightly underlit.
Bear in mind your focal lengths, I would probably say use 1/50th. Your flash will freeze the subject motion anyway, and a little bit of ambient background motion blur might make it quite dynamic. Aperture prob something middle of the road to help ad hoc depth of field... say f5.6? Then its just a case of setting your ISO. You can go fairly high with both your cameras, though shoot RAW. Buffer depth goes out of the window when you are waiting for a flash to recycle so don't worry about card speed.
I would use E-TTL, set to -1/2.
Slight under is easier to recover than even slightly over.
With your flash on an E-TTL lead you can keep it quite far away from the axis of the lens, and you can model slightly, throwing the shadows away from directly behind your subject. Have your camera on a long strap though, in case you end up juggling, that way the camera won't fall.
Plan b. A cheap macro ring light, dead basic pc synch type, set the thyristor to A, and follow the quide on the back. Nice fall off. Quick and Simple.