I have a 8.5x24 car hauler, and no tow mirrors. I put the extenders on, but it’s more for appearances, the normal mirrors work well and I’m not seeing behind me either way. The BLIS does work, displays an icon telling me I have a 30ft trailer, but I’ve noticed the BLIS needs to ‘see’ the trailer real soon after activating tow/haul mode to come on. I usually wait until I’m ready to roll before activating tow/haul and as I make the first turn the screen flashes some message (I’m always watching the trailer) and the 30ft icon is lite. I too have a wireless cam on the back of the trailer so I can see traffic behind so I’m not surprised by it.. I’ve watched the traffic and the BLIS indicators and been quite amazed how well they work.
I probably would have preferred the tow mirrors, but didn’t want to lose the folding function. With the extenders and wireless cam I’m happy with the rearward visibility.