Oil Leak Advice...

It's been a while since I've been on the forum- still take a look at it every now and then, just haven't been too active. I've had the truck for a bit over a year, and the entire time of ownership has been fighting with a persistent oil leak. Truck is an 08 Nismo crew cab, about 45k miles currently (purchased with 34k miles). Leak is on the drivers side, and I think I've narrowed it to the very front of the valve cover area. First two fixes, done by the Nissan dealership I purchased from, were replaced valve cover gaskets. Each time, leak returned shortly after. Most recently, they replaced the entire cover, but with less than 1k miles it looks like the leak is back. Oil leak spreads down valve cover gasket and the area below if I don't keep it cleaned up, and occasionally must drip onto the exhaust manifold after long drives because I get a slight burning smell when I pull into the garage. At one point they did add dye to the oil, but there was no obvious source.

Since it doesn't appear that it's the valve cover or gasket, I'm wondering if it may be in front of the valve cover, perhaps around the timing chain cover? So far the dealer has warrantied their repairs, which was initially completed under a used car warranty, however it clearly hasn't fixed the oil leak that was identified shortly after purchase. Any insights into other sources? Any recommended tests?

Overall I really like the truck, and I'm never going to be able to replace with a similar low-mileage truck for the price. However, this leak is driving me nuts and I may be forced to unload it just to get rid of the headache... If the Tacoma had a seat that raised up, I may have already made the change...

Thanks in advance!