Not specific to Norwegian Air, but I always try and keep my carry on bag at less than the allowance.
I have had my carry on bag weighed twice, once at Gatwick and it was just over. I was asked to remove something so I removed the flash gun and was told it was okay. The flash was still in my hand and he let it through and I just put the flash back in the bag.
The other time was returning from Majorca and quite a few passengers had to pay extra.
I have a jacket with lots of pockets (either a fishing or photography jacket, not sure which), I put the heavier items, camera body and 70-200 f2.8 and other items in the pockets.
I have a silnylon bag (weighs nothing to a camera bag) to go through check in.
I have some lens pouches in the silnylon bag to transfer the camera equipment to when leaving the airport.
I wear the jacket with the camera equipment through the checkin. Its easy to wear through the security check as it can be taken off and placed in one of the trays and then put back on.
I don't tend to return the equipment to the bag until I am on the plane in case they decide to check the bag at the gate.
Having been to Finland in winter I wear a down jacket over the top, once on the plane I take the down jacket off and I take the jacket with all the camera gear - body, at least 2-3 lenses - off and place it in the silnylon bag, which has my laptop in it as well.
If I'm taking a camera bag I put it in my hold luggage as they can weigh a substantial part of the carry on allowance.