hi @Ross K.
This is something I will be working in more detail myself soon, so I am no expert but had a few thoughts if I were writing it and planned to make a signed legal document out of it.
Try to always use statements with the scope as defined as reasonably possible. For example you said "remove all existing toilets" which is great a perfectly clear doesn't leave anything that will be a question of your interpretation vs the GC's.
On the other hand "removal of damaged sheetrock" may possibly lead to (contrived) you believe it is water damaged and should be removed, GC believes it is just discolored and only needs fresh paint.
That's just an example and maybe the easiest way to attack that kind of thing without having to spend a massive amount of time and energy would be to have a clause about the "acceptable condItion" which is your discretion not the GC or maybe a short list of definitions that is standard across all your SOWs that define acceptable condition....
If you have RocketLawyer or know a great contracts guy I am sure they could help fairly quickly.
Again, no expert but that is what came to mind, I will be interested to see the other replies.
-Keith