Crossbars? Roof rack? Hopes and dreams?

Hello! I am a former sedan driver who is now the proud owner of a 2015 Lexus RX 350. And while I thought the RX was too bulky at first, I’m really leaning into it—especially as a new homeowner.

I can fit a lot of stuff in the car with some angling and finesse, but I’m about to pick up a long, heavy umbrella (in box) which, at 8 1/2’ long, will definitely not fit in the car.

I had assumed I could ratchet the box to the roof rails, but everything I see is telling me I need a roof rack or at the least crossbars for my roof rails. My family has used the rails for Christmas trees since my father bought the car in 2015; is it completely dangerous to attach this boxed patio umbrella to the roof rails for about 50 miles?

Thanks in advance!