Speaking as someone who's shot hundreds of weddings for over 30 years, my first piece of advice to you, in your situation, would be to keep everything simple for yourself. More equipment means more stress in your situation. And it also takes your attention away from the event at hand if you're spending time working with equipment.
Don't over-think a lot of extra gear. Don't over-shoot it, either.
My guess is it's a simple, civil ceremony which will probably last 15 minutes and once the ceremony begins, the 70-200 will be your best bet.
With a total of 50 people, and four hours of coverage, you should be able to cover that quite well with 200-250 GOOD, unique images, max. You'll shoot more than that (duplicates/multiples) but edit down to the best. You don't need to give your client 1000 images.
Don't shoot just for the sake of shooting off frames... Make your shots count!
For the type of event you explained (outdoors), I'd travel light. Body/24-70 & 70-200/flash for fill.
Familiarize yourself with shooting high speed sync since you'll be shooting in full daylight.
I could go on and on, but in the end, keep it simple for yourself.
For formal pictures and groups, work on simple, clean poses with good backgrounds.
Look for examples online.
