Well the gear would be safe in the car trunk but keep in mind how hot Vegas is, for example. You are looking at a high of 35 C next week, so it isn't really so good to keep the gear in the truck for too long, unless the car is in a covered garage perhaps. But even then. Also keep in mind that airlines consider any extra bag like the one for your 70-200 as an additional carry-on item. Keep the things you carry to a bare minimum in terms of number like one main bag then a very small item (purse, etc.). Again, double check the airline regulations. They can be very difficult to deal with if they are sticking to the letter of their regulations and have a full flight with very little extra space.
I think sharing a DSLR would only strengthen a relationship, LOL. But what are the odds of one of your cameras completely failing? But it is funny to see your relationship dynamic. It reminds me of when I first got my D700 and my wife wanted to use it and I said no way and she said "what is yours is ours and so its mine too!" So I got her a D7000 so she wouldn't bug me to use my camera. Cameras are a very personal thing,
. But it would be funny to see you two at the rim of the Grand Canyon fighting over which lens you can use, hehe. And as far as I'm concerned, any trip with the wife is a test of the marriage, hahah.
I think sharing a DSLR would only strengthen a relationship, LOL. But what are the odds of one of your cameras completely failing? But it is funny to see your relationship dynamic. It reminds me of when I first got my D700 and my wife wanted to use it and I said no way and she said "what is yours is ours and so its mine too!" So I got her a D7000 so she wouldn't bug me to use my camera. Cameras are a very personal thing,