I usually carry a regular size back-pack and am able to easily hold it between my feet on all the rides ( never done rockin roller coaster - but everything else !)
I try to travel as light as possible - and if my camera would only fit in my pocket I would not carry a bag at all. Many of the larger rides have only a small place for your bag and I have been hit in the head by my onwn "flying camera bag" when trying to hold it on Tower of Terror.
Yes bags are OK on all the rides at WDW . Some have hang clips and many have Nets to put them in . But most you can put at your feet and put your feet through the straps.
Most don't have a place to put things. I always put everything between my legs on the floor, including RNC and it is fine. Just make sure everything is closed on RNC.
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