You can if you've paid:
Customers can pool or share their purchased baggage allowance with other passengers included in the same flight reservation when checking-in together.
For example, if a reservation has two checked bags of 20kg (40 kg in total) one of the bags could weigh 15kg and the other 25kg (40 kg in total).
I reckon you won't be allowed - Ryanair are such gouging fucks, there's no way they won't use it as an excuse to chuck the bigger bag in the hold and probably charge you for the privilege.
Back in the good old days, you could do basically anything on airplanes and airlines wouldn't bat an eye. But nowadays, there are rules and restrictions that so
www.cleverjourney.com
Can Baggage Allowance Be Combined for Hand Luggage?
Usually, combining the baggage allowance for hand luggage between different passengers is prohibited. For instance, you’re flying with your friend and both of you can have a 10 kg (22 lbs) carry-on, you can’t pack 5kg (11 lbs) in a single carry-on, and 15kg (33 lbs) in the other one – each one needs to be below 10kg (22 lbs.)
Do what one of my mates did a couple of years ago - wear all gear. He's a boarder so got away with boots too