I use a soft belt with a pump case, or just clip the pump to my nightclothes. I don't notice it and I've never had a problem with tubing.
I don't like leaving it beside me unattached as the few times I've done that, I've got up, forgotten it and leapt out of bed - only to be reminded of my pump with a shock as it pulls on my site and dangles merrily in thin air!