Newbie needs help with first time concerns

Hello everyone!

This summer, my friends and I are planning a road trip through Belgium and the Netherlands. We’re all first-timers, so we have plenty of doubts and concerns, but we’re hopeful that we’ll find solutions along the way. We’ll be traveling for 10 days, staying mostly in tents and hostels.

We plan to rent a car (or two if some last-minute travelers join us), but our main concern is whether all our luggage—a small trolley and a backpack per person, plus one tent for every two people—will fit inside the car(s).

Are we overthinking this? If not, what are some practical solutions? Any advice would be greatly appreciated. Thank you in advance!

EDIT: we will start the trip from Italy and fly to Bruxelles, so this might be a problem too