There's no way to seal the leaking spark plug tubes without new rocker covers. They're unique to the engine, and quite expensive.
That's probably the reason for the silastic. Used sparingly on scrupulously clean rocker covers; I don't see a huge issue.
That said; when I changed my first set of plugs, the rear plug was absolutely swimming in oil, and the car ran perfectly.
Not saying it's not the issue with yours, but it may not be the "magic bullet" you're looking for.
I wasn't aware that yellow jackets had been made to suit the VQ25Det; and VQ35De yellow jackets are not compatible as far as I know.
OEM coilpacks are the best choice hands down, and at around $100-$120 per coil brand new it isn't the end of the world. 2nd hand, they can be found much cheaper.