i recently asked a MDS which agonist had the least side affects and he said NEUPRO.
bottom line, sinemet (carbidopa/levodopa) is the gold standard, not sure if you have tried it but you could do a short trial, 1-2 weeks and see how it does and if it really helps have peace of mind that there is something that works.

issues with neupro are cost, will your insurance pay for it, and skin irritation. it's still an agonist so you'll probably have side affects but because it's transdermal and continuous delivery, you'll be taking a lower dose.