You can download a pdf of the Gougeon Brothers boatbuilding book for free...
https://www.westsystem.com/the-gougeon-brothers-on-boat-construction/
If I remember correctly, epoxy glued joints should not be clamped as tightly as regular wood glue joints, tight clamping weakens the joint.
For billions of clamps, you might be able to use pvc clamps...
Bungee cords are another alternative or strips cut from old inner tubes. Sticks placed strategically and the board wrapped with string or rope can work. Screws and sticks can work, with the holes filled afterwards.
If you ever want to experiment with vacuum bagging, people often use a shop vac and polyethylene plastic. I've used compressors off of old refrigerators and ACs, you just hook up to the vacuum side of them.
A friends SUP de-laminated, he had no clamps so we took it outside, supported it on the bottom, re-glued the top, put a piece of polyethylene over it and then a bunch of dirt to apply pressure while the glue set. We called it dirt bagging.