As someone once again playing around with the idea of building a Velophot (Afghan Box Camera/Kamra-E-Faoree/Camara Minutera, etc.) I worked out a process for doing this and either going ahead and building that camera or using my Calumet 4x5 with either a darkroom box or a changing bag and Stearman SP-445 Tank.
The thing that keeps me from using Direct Positive Paper or using paper/film reversal processing is my need/desire for a negative. I like playing around with paper reversal with the Pinhole Stereo Camera I made and other muck around sort of stuff, but I'm pathetic when it comes to giving away one off prints - a key reason for my first camera NOT being a Polaroid as I'd originally planned!
With regard to photographing people on paper, I meter at ISO 3 and get 1/4 or an 8th outside in the sun. For the reversal processing I use, I add three stops, bringing me to 1½ - 2seconds. That's at f11 - opening up a couple of stops would make that absolutely doable.
The ones I've done inside were obviously significantly longer.
In terms of having a wet paper holder, rinsing it off and wiping it down between exposures to then reload in a dark bag doesn't seem like a problem to me at all. I've never done wet plate Collodion, but I imagine it's not entirely dissimilar. Either way, I can't see a point in the process where it would be necessary for anyone using the Stenopeika kit to be putting a wet holder in a changing bag or camera.