Well I can do 2.5 weeks on ryanair's (paid) hand luggage - so a 10kg case and a personal bag. I think I could manage 4 days even without a capsule wardrobe.
When I was away for 2.5 weeks I took 5 dresses, 1x shorts, 1x trousers, 1x raincoat, 1x jumper, 1x leggings, 4x tops, 1x sandals, 1x converse, wore walking trainers, 1x swimming cozzie, 1x microfibre towel, 2x nighties, 14x socks and pants, plus all toiletries other than a 200ml sun cream I bought at the airport.
So for 4 nights I would take:
1x nightie, maybe 2 if I didn't have aircon
2x shorts + team shirts for the two days there,
2x dresses/evening outfits for those days, to be reworn as day outfits on 2 other days.
1x outfit to go out there, including a jumper if you want one.
Wear whatever trainers you'll want for the Grand Prix days.
Take another single pair of shoes.
Pack a single pair of trousers or some leggings to wear if it's cold.
Spare t shirt/dress for safe keeping.
Done.
That will easily fit in a small carry on suitcase.
Liquids and anything with a battery go in your personal bag so you don't have to unpack the suitcase at security.