Michael, I've only been doing this for a couple years, and hopefully a lot of people feel the same, but I have three personal rules for setting up evaluations: 1) Contact the club/course as far in advance as practicable, 2) Accommodate their schedule, and 3) Always expect to pay. Sounds like you have the same philosophy. I've heard from too many places that a lot of raters don't live by these courtesies.
I just got back from a trip to Maui where I was able to sneak in a couple rater rounds (don't worry, JK, it wasn't work related). Kapalua Plantation charged a reduced rate, but by giving them plenty of lead time, they were able to accommodate my wife as well. My guess is they send raters out right before the twilight rate kicks in (rater rate was still lower), and they paired us with another panelist. No complaints on playing an afternoon round instead of prime time. It allowed us to schedule a dinner at Merriman's since we were already up there, as we were staying on a different part of the island.
The other round was at Makena. I was told I'd probably be one of ten people on the course all day. First class service, which is to say they treated me like a member. It's Discovery Land Co., so I'm not even sure they're set up to accommodate guest play, or at least charge guest fees. They wouldn't even let me tip the valets. But they told me that they get people who show up and slap a rater card down and expect to be allowed on the course without incident. I just don't get that. By the way, I tried to do some research on the place beforehand at this site, and there was a lot of conjecture. Current skinny is 18 holes redesigned by Dennis Wise from the original north course. Paspalum in just about perfect condition tee to green, and an interesting layout worth seeing. They paired me with an assistant pro who worked on the construction crew, and was a fount of information. I don't mind playing alone when I'm on a rater round, but sometimes it's nice play with someone who knows a bit about the course.