If you can't say no to them and you're being polite about it, inform them that you have limited weight and can only spare them the specific amount of weight that you're comfortable with. If they have an issue, then they're spoiling themselves and taking advantage of your situation.

You could even say that the stuff you're leaving behind will, in return, be their turn to make space for when they travel, as a gesture of thanks. Or you can ask for monetary compensation for such inconveniences. I'm sure most of them will dodge asking you for any favours when they realise that it goes both ways. Next time, do the decent thing and not tell everyone about your leave. Keep that stuff to yourself.

Maybe you're off to another city for a few days to stay with friends, or whatever excuse you can garner, basically you visit another city, stay for a few days to get things ready, and then visit the airport to enjoy your quiet vacation.

Khalas. Don't be a pushover, but don't be rude, either.