I ended up ordering a box of 45 Imation 26219 from techforless.com $35.55 with shipping, $0.79 apiece. They’re actually a little cheaper ($0.69) on boomj.com which I learned 10 minutes too late. I’ll see how well they work. They’re matte, +R, with AquaGuard, hub printable. They’re the only +R hub printable waterproof single layer discs I could find and I’ve searched for quite awhile. I’d have preferred a gloss printing surface, but that doesn’t seem to exist. In fact, the only DL +R hub printable glossy waterproof discs I’ve been able to find are Moser Baer. If they can put that surface on a DL disc, I don’t know why they can’t do it on a SL disc, but oh well.
The term AquaGuard (which I assume is a trademarked name) also appears on Primera discs. It will be interesting to see who makes what when I get these discs.
Thanks for the advice and the links. Always more to learn.