Given body size I doubt you will be clean in time. I'm 6'1" 280 lbs and it takes me 60 days to get close enough to use dillution.
Generally when I've had to take both the physical and drug test at the same time, they do the physical first and then let you get dresses and do the UA.
I would store the synthetic urine in my shorts till the phystcal and then transfer the bottle to my pocket and do the physical and then transfer it back to my crotch for the UA. They won't observe you.