* See table below for PVID handling - it's from the first edition of T1600G's User's Guide, which has been replaced already by another version - I saved it for reference. Since the TL-SG108's UG is very sparse, I take this as reference. I think that the OS of the switches is almost the same for Easy Smart and Smart/Managed switches.
Just guessing by my gut feeling. To proof, I would have to set up this scheme and analyze it, like you could do too. It would probably be easier to just set up a trunk port, but if I have some time tomorrow, I probably will test it if you think it makes sense. But I have Unix systems only and they don't send as much broadcasts as Windows does, so my LEDs would probably blink with somewhat slower frequency (no kidding).
Before doing so, please could you test it with just one computer connected to the switch and the switch to the router to see if something changes (frequency of blinking, for example)?