In response to Jorene's question about vests combined with fanny packs for keeping your 24 hr items on your body (in case of accidental separation from your horse), our members use a variety of multi-pocketed vests and fanny pack arrangements. None of the vests I saw on the hivis.biz site had enough storage space.
My own vest was custom made for about $110 out of orange cordura and mesh by a lady in Montana. I used a fishing vest which fit my 5'2 body, laid it out on flattened paper garbage bags and created a pattern with pockets drawn on. You can see the results in a photo in our web site: www.nwhsar.org, past missions & events, back country horsemen poker ride (we were there as 1st aid responders). 2nd photo "bob & barb" shows me with the vest and other equipment representing a 24 hour pack.
There are two 6" deep pockets which run across the back, in front, two 5" wide zipper pockets which extend approx 1 1/4" out. also 2 upper pockets and radio harness. It ends up weighing around 10 lbs loaded and the wearer looks egg-shaped...but it isn't very hot (thanks to the mesh). If anyone wants to contact the lady who made these, I can look up her address (it was 3 years ago, so I don't know if she's still making SAR vests or not).
My unit recently purchased 20 vests which folks are buying for $70. I'll try to get details and a description if anyone's interested. I believe the material's cordura (hunter's orange), with soft fleece neck lining, many front pockets and one big rear pocket which takes the place of a fanny pack.