You have no idea what was changed or customized on your camper since 1995.
This camper has very small holding tanks. They cannot hold all the water from the fresh tank, plus your waste, even combined.
It is likely that the previous owner rerouted the shower and sink drains to the hose that you found, so they would drain outside into a bucket or a blue tote.
When you said, "tumbling down" did you mean a length of hose came out and water started running from it?
As long as the water is not draining INSIDE the camper, do not worry about it. Use a bucket to catch the water, or if the campground allows it, let it run on the ground!
You will be wishing you had NOT "fixed" the problem after one or two trips.
