Never done it but if it was me I would freeze the beans as they are and mash them later when I needed them. Things frozen as mash tend to be sloppy when defrosted as the ice crystals in them are bigger because you have released the moisture when you mashed them.
A couple of things you could do with them is blend them down with some garlic and herbs and creme fresh or cream and make a type of humus - great on celery as a snack. Or blend them with some sautéed onions,herbs and stock and finish with a bit of cream and season well and you have a nice butter bean soup.
I can't do beans, lentils, chickpeas etc as they spike me so I only eat them sparingly but I do love a bit of humus!
Meant to say that the soup will freeze very well
