If the purpose of the calculation is the exercise itself, then you work with the airplane manufacturer's data. For a larger airplane, the data will be in the flight manual, because it matters. It's not there for a 172, and not even for the Caravan. For a 172, I opine that there is more variability in performance result because of pilot technique variables rather than the runway. Of course, you can find a runway which is outside what Cessna published for performance. Cessna is not giving you data for that, so, should you choose to operate from that runway, you're on your own. If Cessna provides data, they become responsible (and liable). There is no requirement that they provide the data, so why would they accept any more responsibility and liability that necessary?
As I have done in such situations, if I need to operate from a runway with unusual characteristics, I go there first either with a locally familiar pilot for their wisdom, or solo and light. I have the wind favouring what I'm going to do, and practice. If 100 feet of ground roll is a make or break for safety, I should not be there - either ever, or under those conditions. A few times, I have waited either for cooler weather, or more favourable winds, or not taken the load.