There's a difference between 'tinkering' and sensibly rotating, though. In this of all seasons, especially in the next few weeks, we simply won't be able to start with the same starting XI each week. I agree that we probably don't know our best XI, especially given we haven't seen how a midfield of CB and MM together works, but, even if we did, we would rarely be able to realistically start with it.
And also, again, this of all seasons with the five subs, it's very much a squad game. One of my favourite things about KR is his ability to identify where we're having issues and bring on players / change shape to rectify it. The five subs gives him so much scope to do this - if you look at the Wigan game, for example, he made two attacking subs (bringing on Shodipo and Lee for Gorrin and Kelly) and then, after we went ahead, was able to make two defensive subs to shore us up (Grayson and Hanson for Sykes and Barker). In usual circumstances, doing the first would be absolute suicide - abandoning the midfield with a quarter of the game still to go would leave you hopelessly exposed. But because of current conditions, it gives him a bit more freedom to 'tinker'.
I guess the point I'm making is that it almost doesn't matter that we don't know what our specific strongest XI is. What is important is that we have a squad and a manager that are capable of adapting to the situation if needs be.