Years ago, I googled quite a bit into the timing requirements of the CAN bus, and actual experience gained by the others. After all, sometimes looking at the issues faced by others is far quicker than making all the mistakes yourself. My outcome, and my advice to myself I ended up with is:
While the CAN bus is specified to work with fairly high clock rate error (don't remember the exact figure, around +/-1%?), I found several academic and practical studies proving that the bus design doesn't work reliably with clock errors nearly outside (but still within) the spec, and thus, recommend adding extra margin for the allowed clock rate error. I.e., people who trusted the advertised "robustness" and used inaccurate clock sources, were fucked.
While CAN bus can definitely be made to work with RC oscillators, if I'm not wrong, CAN is mostly used to provide robustness in medium- and high-cost systems - not lowest cost, nor lowest power.
Robustness is a complex issue, and because not everyone has equipment and time to perform exhaustive analysis over selected parameters, in my opinion, a system that requires fine-tuning parameters to compensate for inaccurate clock source, to work reliably, will be inherently less robust. If adjusting the parameters is critical for the system to work, this means there is little margin for error left, possibly even with the "optimized" settings. With an RC oscillator, everything should be measured over full operating conditions (temperature, voltage, unit-to-unit differences)...
Hence, my end result was: if I choose to use CAN, I always use a proper crystal oscillator to clock the CAN devices. Sure, this gives 10-100x less worst-case clock error than what would be "allowed" by the CAN specification, but this also makes fine-tuning timing parameters less critical, and saves a lot of my time. For the BOM, this is of course a $0.10 increase.
What I found is that with a typical low-cost crystal source, the situation is indeed "far more accurate than CAN could ever need" - and the setting for SJW is irrelevant, 1 is enough.