Todd, I doubt how would your SP provide you guranteed QOS SLA's with that setup. As there is no one to one mapping of PREC/EXP values to FR based QOS.
But although, if he gurantees or ensures that the FR access cloud is never going to be congested and everything is fifo in there then he can provide your per hop QOS behaviour based on your PREC value across the MPLS cloud.
HTH-Cheers,
Swaroop