My experience with valves is no tools are necessary except a valve wrench and pressure. When the boat is inflated the pressure holds the back nut allowing you to tighten and loosen without grabbing the nut on the inside. At least my experience with Maravia and Aire with leafield
How far away are you from the rental or another raft rental place, how long is your trip, how many other boats in your group, and how fucked will you be if your repair gives out on day one and you have to repair it every day of the trip ? or if you have to return two days later than intended
I'd error on the side of caution. You dont want to be stranded somewhere with shit gear if its gonna mess up your trip. I'd rather launch at 4:30 and have a good float then get out at 10am and have to deal with this issue for the whole trip
Much easier to make up miles by running less working boats or perfectly working and maintained gear then to be hobbled by crap gear
Hey, if you want me to take a dump in a box and mark it "guaranteed", I will. I got spare time.