My 2 cents. I was a lineman at one time and there are a number of things that I don't recommend but do have the solution for.
1) The barrel typically is made in a way that one side is longer than the other. It is possible the installer put the long end on the inside to make it easier to attach the coax. If that is the case and you have rear access, flip the barrel.
2) Slip ons last about a dozen pulls before they get stretched out. We were not allowed to use them with our meters because of the signal loss and poor contacts. They also leak RF signal like crazy, giving you and possibly some of your neighbors crappy picture.
3) The tool is the way to go unless you lose it. Which you will.
4) What I did was buy a double male barrel and put a female barrel on the end. I also used heat shrink to prevent them from coming apart which isn't completely necessary. Leave it attached camper side. This fits without any issue and when it wears out in 5 years, you can replace it all for about $2. (Shipping can be the killer but I already had some.)
Double male Amazon.com: Skywalker Signature Series F-71 Double Male Barrel Connector, Each: Electronics
Standard barrel: Robot Check
2015 FR 29V Vengeance Toy Hauler
2015 Honda GL1800 F6B
2009 Dodge Ram 1500, Total Load Control air bags, Blue Ox Swaypro.
Technology presumes there's just one right way to do things and there never is.