I've used the Remora skimmer for years. It works, but I've never worried it could pull too much out of the tank. I know what you are saying, but I don't think it is warranted.
Lower the O-ring a 1/4" and then let your skimmer work for 48 hours. Check the skimmate.
Ideally, you should clean it daily for best results, just rinsing it in the sink and wiping it out as best possible. If you have a reef-only sponge to clean it, that would be fine. A reef-only toothbrush would be good as well. And every two months, you should use the small brush to clean out the spray injector in the Remora, which is located beneath the collection cup.