Carry-on luggage restrictions in Greece
We will be doing some inter-island flights on Sky Express and Olympic Air. I looked up their carry-on restrictions and it appears weight is limited to 6 kg on Sky Express and 8 kg on Olympic Air. Also, the size limits are smaller than US carriers - 17.7"x13.8"x7.9" on Sky Express and 21"x15.7"x9" on Olympic.
I have a backpack I was planning to take that is 23"x13"x9" but last time I took it on a trip it weighed closer to 16 kg fully packed. The bag weighs about 2 kg empty.
How serious are the airlines about enforcing these carry-on limits? I don't see any way that I can carry on only 6 kg including luggage weight for a 6-week trip. Should I resign myself to checking a bag, or should I buy a new carry-on that is smaller and lighter?