I wasn't really thinking in terms of cost plus but I have never heard of a per diem being anything more than something to cover expenses while traveling. My understanding of a per diem is not meant to be a daily bonus.
If they pay it then it's all the better for the op. I was more curious how much blowback the gp has gotten on a large per diem like that and how they would go about countering it for my own personal use.
If I'm going to travel to someone's site to perform, they want every minute offsite to be completely stressless and relaxing, so I can focus my onsite time on work, not on sleeping.
That means good hotel and air accomdations, car service, luggage handling, ...
If they pay it then it's all the better for the op. I was more curious how much blowback the gp has gotten on a large per diem like that and how they would go about countering it for my own personal use.