I would definitely take a spare riflescope, because anything can happen on a horseback hunt, and the most likely part of a rifle to get damaged is the scope. I've had a spare come in handy on several hunts in various places over the years.
Ideally it would already be in the same mounts as your Zeiss, and also sighted-in at home so it could switched out quickly, and not need too many of your 40 rounds to be check-fired. But just a scope will work too, though it means taking the right screwdrivers for the mounts, and more rounds to make sure it can be zeroed correctly. I'd take another box. A fixed 4x isn't considered ideal by most of today's hunters, but will definitely do for moose and doesn't take up much room.
I have gone back and forth on this as my one prior experience with Talley detachables was not great. But even though its a German Zeiss - scopes do fail. I have a well worn, but trusty and repeatable Burris FF2 3-9x (Made in USA model) that I think I am going to take, with an allen wrench, for just in case scenario. This should only add just less than 1 pound to my gear.
