How to nurture volunteer blackberries in my raised bed?

I have a bunch of 4×4 raised beds in my yard. One of them has a cluster of volunteer blackberries growing in one corner of it this year! It’s semi-shady and annoying to grow anything else in, so maybe I’ll have a raised blackberry bush in there instead. Is this a good idea? Should I just tip-layer the canes and let it go to town, or try to trellis?