Airbus guy here...
Do those aircraft not have a way to calculate a reccomended max altitude for the GW based on current conditions, eg SAT and ALT? Obviously caution would be exercised as you cross jetstreams into warmer air etc, but there isn't any specific guidance here other than to not fly above the REC MAX altitude produced by the FMS.
In reality, most of us probably wouldn't bother climbing there unless there was perhaps a 1000ft margin to the REC MAX (the true service ceiling is higher than that but the A320 FMS doesn't identify it for us).
Please appreciate that Im unfamiliar with Biz Jets, but I find it surprising that the FMS doesn't give some sensible guidance on the subject as it's simply maths and a lookup table - instead relying on some old hat knowledge that rudestuff suggested are inherited from a previous airline/aircraft/era. My airline has only ever flown the 737 and the A320 so the operational baggage in that regard is somewhat limited.