I attempted a modified version of the OP's method using vodka instead of grain alcohol (not available for retail in VA) and with a couple liters of honeysuckle from my backyard. I found the honeysuckle extract to be awesome after about half of the liquor evaporated (used a small fan to blow over the dish), but it turned nasty (oxidized?) well before all the liquid evaporated.
Looking forward to trying it with some of my backyard hops in the month or so. Going to pick up some grain on one of my trips to NC.