Just buy a mesh safety vest and weave some small size tubing into the mesh. It will be easy to slip on or off and will still breath well.
You actually DO NOT want the high transfer rate that copper tubing would offer because it would be almost painfully cold. It would also be uncomfortable to lean against.
You won't need a very high flow rate, so you can try a windshield wiper pump first. But any submersible pump will work fine. Even AC fountain pumps will work if you power them through an inverter.
http://www.fosterandsmithaquatics.co...fm?pcatid=8164