here's a recommendation: buy two pocket wizards and a pocket wizard remote trigger cable. put a wide-angle lens on the 7d and a telephoto on the 5d. whenever the 5d fires, the 7d captures the whole scene. works beautifully for sports.
I'll give it a try when I get the 5D3, thanks for the recommendation.
Trent
EOS R5 with RF 24-105mm f/4L IS USM lens, EF 70-200mm f/2.8L IS II USM, Extender EF 2x III, RF 50mm f/1.8 STM, RF 35mm f/1.8 Macro IS STM, RF 16mm F2.8 STM, GORUCK GR-1 with TrekPak insert