As long as holding onto it doesn't result in you orienting your body away from presenting the most area to the oncoming air. Don't hold onto a beach ball for example.
Juliane Koepcke, one of the only people to survive such a fall, did it strapped into a row of seats. And when she landed she was in good enough shape to survive 11 days in the Amazon rainforest (!!!) and make her own way to safety. So I'd say statistically, it's about the best thing you can do.
“If thus connected, you have some questions to address. Is your new conveyance air-worthy? […] If you choose to go it alone”
Also, even if it is dropping faster, it may be worth it to stay in your seat if you can use it as a crumple zone
Which isn't to say you won't feel your seatbelt tugging on you. You will likely be straining painfully against it. But that's because you'll be tumbling wildly, the entire assembly battered and buffeted by huge forces.
Weight/mass doesn't matter, as all objects of the same shape above a certain density fall with the same speed. So literally just pick the widest object you can find, no matter how heavy it is, and ride it.
Terminal velocity occurs when the drag force balances the gravitational force. So F_d = F_g
F_d is proportional to the area of the object and the velocity squared.
F_g is proportional to the mass.
So, for constant area, at terminal velocity we have v^2 ~ m or v ~ m^(1/2) where "~" denotes a proportional relation.
Thus a heavier object falls at a higher terminal velocity than a lighter one.