They would have to just hang out and not really be able to leave for 5-6 hours while our other friend is working, but could do their own thing. Basically they are just there for safety reasons if anything happens to our friend doing the work who we have a fair price established. First friend has a lot of sedentary hobbies so boredom isn't a risk but I want to treat them fairly.
You can always ask them, just make sure they know the deal and see what they think is fair. They might be willing to do it for not much just because they like you, and coming in real high might make them feel like they're obligated to do more than you're actually asking.
If it's literally just "we want someone in the house in case they fall, and to keep eyes on when they're doing something dangerous/occasionally flip breakers" that's definitely something most people would do for beer money/dinner/IOU especially if they had no other plans.
Coming in with a big hourly offer can definitely make someone feel weird depending on the work and their relationship with you, but that's between you and them.
Lol one friend told me not to pay him and one (unemployed) friend told me I should have hit up all our unemployed friends first (esp. them lol).
Sounds like you've got your answers lol