Well, here's the story behind the question. I'm in the process of adding new plants to my tanks. Usually when I do this, I will buy my plants one day, and put them in the tank and let them float around until I drop the water level for the weekly water change, and then plant them. So, the last couple of weeks there have been plants floating around for several days, and on occasion I've seen a tail hanging down from the floating plants. This makes me wonder if they have an inclination to occasionally breach. I might put in a turtle dock to see what happens. Will keep posted.I think that if they do that, it's to either find food or to possibly escape undesirable water conditions in search of better ones. Either way...your captive ropefish should not have these concerns. If they are well fed and well maintained, I would bet that they will never use such facilities.
Fish...even lung-breathers like ropefish or walking cats...are unlikely to go for a stroll just for a breath of fresh air.
Build something and try it...keep us posted, please!