If you're optimizing for clear and damage in the early game, try taking MPen glyphs instead of resistance.
Since Shen has sustain and a shield, it would be silly to optimize for tankiness in the jungle. Either you can take flat AS for more autos and more passive procs, or you can take hybrid pen marks / quints to do more raw damage with your Q, passive, and autos. If you want to have relevant damage to laners and possibly late, the latter would be better.
So, what I would use for Shen jungle is probably something like arpen/AS marks / flat armor seals / mpen glyphs / mpen quints. Because Shen relies heavily on his ultimate to gank, I would not personally bother with move speed. My reasoning for taking so much mpen on Shen is that everything outside of autos is either utility or magic damage on Shen. It increases your early damage output from just your kit, and later, I would build Devourer / Wit's end on Shen. The combined ten or so mpen with the twenty five resistance reduction could definitely hurt ranged squishies, since they do not have scaling MR outside of runes and masteries.
As for masteries, he has sustain and a shield for the jungle. You do not not necessarily need to optimize him for tank unless that's the role you're filling. It would be better to optimize him for clear. Shen can really put out of a lot of sustained hybrid damage, so the penetration, damage, and blade/spell weaving masteries in offense are easily very good on him. If you do optimize in offense, keep in mind that the extra AD in offense is going to benefit you a lot more than the extra AP in the early game.
I regularly play off meta junglers, but this is the first time I've given more than a few seconds thought to how I would do it with Shen if I had all the right stuff. Good luck!
EDIT:
I now realize I repeated myself a lot. //facedesk