I've done 1200 sectors, so I do know a little about packing a suitcase.
And now I've trained the wife.
We follow BladePilot's advice:
"When you leave drop off what you bought at a charity shop or shelter facility for the needy. It'll cost you a damn sight less than £180 and you'll probably feel a whole lot better for"
We take full baggage allowance outbound on our Longhaul Trips (eg Colombia, Miami, Hong Kong etc)
old T-shirts, shorts, underwear,
old everything including the kids' clothes. We give the lot away to charity as we leave.
15kg in a wheelie is easily sufficient. You're not going to be wearing winter clothes by the pool are you? Are you planning to tie the knot again and get married on every day of your stay in Cuba?