Thinking outside the box, nice.
Read the regs..if you're asking basic regs questions like this, one wonders what other important info you have also missed..
Multiple presentations on one setup is a fairly common approach while plunking for salmon/steelhead (which I believe is done on S Santiam), but wouldn't work well or at all when casting & retrieving (eg with spinners). Maybe with bait, but I think your energy is better spent going hard with one bait before changing to another, rather than fussing with a complicated rig with multiple baits (I mean for salmon/steelhead).
On the other hand, the multi bait rig (for perch bullhead etc) you describe could be worth a shot in the reservoirs. It's an interesting idea (though locations/times where that many species are actively feeding in one spot are rare). My instinct tells me that having multiple rigs pre-made to switch out on one rod (rather than fished at once), or having multiple rods rigged differently and ready to go (I've found so many cheap used rod/reels at Goodwill etc for like $5-10 so don't say it's too expensive) would be the more efficient use of time/energy.
If you have success with an oddball rig let us know!