One of the hardest--most uncomfortable questions there is.
If you're an individual it's pretty straight forward--Tip what you feel is appropriate for the level of service received. When you're with a group you'll be up against as many opinions as there are personalities in the group & it can get messy.
Then if the guide is also the owner of the operation, why would you need to tip him, he already has his profit & wages baked in the price charged.
The percentage equation doesn't fit at times. When & what do you apply the percentage to? Do you figure it on the overall package price of the lodge package, or do you apply it to just a daily guide fee? How do you know what the actual daily guide fee is in a package price deal?
Tipping is a messy deal. If you're just tipping the guide only. I'd say fifty to a hundred bucks per day depending on the level of service, the success of the hunt and then follow what your gut tells you & your pocketbook is comfortable with. Another rule I use is to always tip individual guides in cash.