I have had a little bit of experience with air equipped vehicles. As for going with copper lines to your air shocks, I would not connect the copper line directly to the air shock but use a piece of soft line between the copper and shock. Again that defeats the use of copper lines directly to seal for any leaks. If you have a trike that has a lot of vibrations the copper line will eventually break leaving you in a serious stranded position. It will also kink leaving no air going to your shocks should they lose pressure or will make one shock not inflate or not properly inflate to desired position.
You can buy those air shocks from Air Ride Corporation who Manufacture those shocks. Google the company name and have a look around their site and you will get a phone number and can call them and pick their brains about the bags.
Also Goodyear Air products also have I believe those bags. Again Google and call them and see what they have. I hope this helps out.