Are you talking about the backrest/seat tube-style valves or the little red tab-open valves that you see on camping pillows?
This doesn’t work with the tube-style valves because the pins get in the way; I haven’t tried the other ones, but I suspect it might work if you don’t mind where the pins end up on the other side. The one caveat is that the little air windows on the side of the valve (theoretically designed to increase airflow and not create a backward flow in the boston valve) might stick outside and let air escape that way. That’s also what happens with the tube style valves anyway.
