Actually, and not to throw a wrench in your plans but I'd be remiss if I forgot to mention that you should probably think long and hard about mirrorless solutions at this point, or at least keep it in your orbit. I don't shoot weddings anymore (much), but photo is still my profession and for most purposes I'd say that Sony, Fuji and even M43 (olympus/panasonic) are both making better solutions for the documentary minded photographer these days. The weight to IQ ratio is unparalleled at this point. If you're going to be schlepping the weight that Canon and Nikon inundate you with you could be getting 50 MP medium format quality at this point. The more weddings you shoot the more the weight of these kits becomes a thing you could live without, and I am an in shape guy who is in the gym 6 days a week.

So, it could be a good idea to spend that money on one of those mirrorless solutions with a starting prime that complements your Canon stuff. For awhile I shot Nikon and Sony side by side until I finally ditched all my SLR stuff because it was dead weight.