yes!!  I use an aluminum clip.  That name?  starts with a "C" and I can't spell it right now.  It is a smaller version of what climber use.  But smaller and not too obvious.  But nothing falls off of it.  Plus they don't break.  

Carabiner is what you need.

Agree with Dave that you should use a carbine. 

You can get them in every sport shop which has climbing stuff

I second the use of a carabiner.  Very easy to remove when needed, but very secure when you don't want it to move.  I use one for my range finder and I've never had an issue.

I wrap my towel through the trunk handle on my bag  seems to work a lot better than the clip