A portable charger, a brand new pack of whatever socks you use normally (maybe 2, switch socks around 1pm, it's the best thing ever for long park days).

And skip the ponchos

https://www.amazon.com/dp/B00LTCLMRS/ref=cm_sw_r_cp_api_kTvgybS7VKC8C

(Sorry I'm on mobile)

This is the best WDW rain solution. It's a rain shell, so basically a reusable poncho. But it's a water resistant shell for camping so you get actual rain protection. It rolls up SUPER small to fit in a touring bag.