We found it. For whatever reason, ours doesn’t have the extended filler neck tube, but at least it does have an oil cap, its just buried down in there.

As far as the manual, this thing doesn’t even have a glove box, half the dashboard itself was just straight up cut out and covered over with duct tape. I’m pretty sure the previous owner did that to make the passenger side into something of a bed for semi comfortable sleeping. 🤷