@mostlybill, It sounds like you have come up with a good plan! Notebook to appointments, wife going with you, written changes from care provider, and a reusable water bottle. As you have mentioned, it is easy to become confused when you get home, especialluy when considering dietary requirements. Has your transplant team suggested or referred you to a nutritionist who is knowledgable about post transplant needs? That is something that might be helpful for you and your wife to consider asking about.

Hydration must be difficult for you to maintain if you are on a job site all day. I have noticed that when men are on a construction site, or when I see trucks going down the road to a site/job, that there is uaually a big orange canister for drinking water. Do your sites have any accessable drinking water for the crew? Have you thought about carrying some bottled water in your car or truck so that when you get to the site, you will be sure to have one?
I carry a reusable water bottle and am careful not to misplace it, and I have several, just in case. My brother used to fill a clean plastic milk jug(s) with water and put that in his truck every morning, or the night before.

Mostlybill, I learned that getting into the habit of drinking enough water on a daily basis takes practice. But over time it becomes a normal routine. Have you thought about recruiting your wife to remind you every morning to take the water? Does she have any ideas for how to help you? How about a buddy at work?