Precious few options east of Zion and all would involve a fair amount of driving every day you want to head into Zion. You'll also still get stuck in the traffic delays at the tunnel as they alternate travel directions.
I guess if you really want to stay on the east side, try finding a boondocking location. Not the easiest thing as finding a good land ownership map isn't easily done. You could try
this site. Zoom to the area you are interested in, mark "Land Status" in the lower left hand corner, highlight BLM Lands in the left menu and see what you can find on a satellite image that has a place to park. I spent a little time trying this and found few places where it seems that a campsite was obvious, but you could spend more time and find something. You might also highlight State Lands as those are sometimes open to dispersed camping also.
There are also BLM lands west of the park around Gooseberry Mesa where I've seen people camping but it's been a few years and I can't point out a specific place to you.
Good Luck. Not an easy task.
Ken & Allison
2 Camping Cats (1 diabetic)
1996 4Runner, TRD Supercharger, Edelbrock headers
2007 Fleetwood Arcadia, Honda EU2000i
4 mountain bikes, 1 canoe, 4 tents, 8 sleeping bags, 2 backpacks
(You get the idea!)
