Im still gonna recommend stopping on the way back too, that is if you have a full boat. Keep in mind now your leaving out of some of the highest mountains in the country, and you need to be light leaving so you can make some kind of climb gradient should a PW545 crap out on you. If its VFR, you can take more. I wouldnt even suggest leaving out of there unless it is 3000-4000 cielings. Actually, I think you need 5000 to leave. Better start looking myself, its getting to be that damn season.
Heres what FltPlan.com came up with:
FL410
4:03 enroute
5,288 lbs burn (w/o reserves)
400 kts TAS w/ 30 kt tailwind
With much stronger tailwinds you could theoretically make it, but it all depends on how many people you have to take and how much $hit they have.
Try to convey to this guy that you can get him there and back in the same amount of time, give or take, by flying lower, going faster, and significantly increasing safety margins with more fuel reserve and climb gradient to play with if you make a fuel stop. He should really look at a Falcon 50 or something of that caliber if its that much of an issue for stopping.
He can spend a half hour on the ground getting fuel or an extra half hour in the air by going high and slow.
It looks like, by your total time, you wont be flying him, but any sane and responsible pilot will tell this guy "I'm sorry, it cant be done without a fuel stop in this airplane" and tell him thats your "final answer". Mountain flying and max range flying are serious, no need to take stupid risks to save "warbucks" a few minutes.
Part of me wishes they'd hurry up and build a dang time transporter or some crap like it for flights like this.