TRYGUY,
IN LIEU OF taking an agonist at night to extend your ON time have you tried 300mg of 50/200er WITH A LITTLE OIL/FAT SUCH AS FISH oil capsule, butter/cracker, etc to try to slow gastric emptying which will extend the availability? just a theory. read a C/L PKG INSERT (ER) on bioavailability.
or set an alarm at least 45min before you predict you'll be OFF, take 50mgIR + 200ER, THE IR should kick in in 45min and the ER in 90min. that might at least remove anxiety. you might have to wake up only once.

Pharmacokinetics and bioavailability of Sinemet CR: a summary of human studies. - PubMed - NCBI