you can attach a strap to a fretless hollow-body bass, but i'm finding that it doesn't really need it. the body is shaped like an acoustic guitar and rests nicely on your knee.

i wonder where you can get a cover to plug the sound hole with, because i bet that's useful to have. less noise when practising at night, and also, if you're playing live and the PA system is loud, it might cut back on feedback.