Thank you to all who posted helpful suggestions as to what it might be...and to those who said under hood fuse, you were right! Hit the auto parts store in town (not towing it loaded with inoperable lights Philsey) and had it fixed before dark. Hooked up a while later and got home about midnight, after driving through heavy rain for 3.5 hours. Glad I didn't have any more issues with the lights!
And for the record, I'm fanatical about trailer lights and maintenance on anything I own. I even hose down the top & underside of my lawnmower after each use if thats any indication. I was already 24 hours late leaving for opening weekend of deer season thanks to my wife's damn BMW power steering pump going out as I was packing the truck on Saturday morning. 35K miles on the car.
Since I was legal driving the trailer as-is, I wasn't about to lose another minute jacking with the trailer lights when I realized they were inoperable. They worked fine with my GMC Sierra prior to the 4Runner. Never thought a new 4Runner wold already have a blown fuse.