If you're just making a regular saddle pan with mild bends, I'd go with 14 gauge. A lot of my sculpture is made from scrap steel and I'm not really choosy about gauge as long as it's consistent on the particular piece I'm working on. I do a lot of MIG work on 22-26 gauge, but I've had a ton of experience working thin sheet. Just keep trying and experimenting with the settings on your welder and gas and you should be able to do 22 gauge on pretty much any smaller welder without too much trouble.
Hooktool, that's some cool shit right there. I haven't gas welded since my sophomore year of college, and probably won't ever do it again, but it's always awesome to see someone working old school at that level.