(Short story) I do keep a spare injector and COP in a plastic bag in glove box. After changing a few it takes me about 20 min to swap one out after reading the code NOW. I have it down to a science after change them a couple times. Not that short of time in the beginning though!
(long story) New to us X-rental 2001 bought in 2007 with a ton of miles on it. Got it home changed all belts, hoses, filters and fluids and thought it would be a good to clean out the engine, so I put some Seafoam in the gas tank. Did I ever get a lesson. For the next 1,000 miles I was under the hood often. I knew nothing about COP's (coil over plugs) or injectors. I thought the engine was blown up. Dug around the internet and found those things miss up often and how to check. Got a good lesson from a "injector" shop. He charged me something like $80 to clean all of them. Got a "noid" for $30.00 which is a little light thing to check cops.
The injector shop suggested to me that
"the seafoam worked lose some junk that was in gas tank for long time and it pass the fuel filter and plugged up some of your injectors. I would change and carry a spare fuel filter and change it every 3,500 miles for about 10,000 miles".
So not that much of a problem after you know what is going on. You didn't mention what motor you have so, my response is based upon you having a "Triton". In your model year I would be more concerned about the plugs. Read up on those things. After getting it fixed you should have many, many miles of trouble free RVing. I would not "cheap out" on parts other than OEM. To many stories about off brands messing up. In a RV if anything messes up you might not be near any mechanics you know or trust.
Check on-line there are a few Ford places that sell low compared to others. It took me about 7 hours to change all fluids, belts, hoses etc. NOT including plugs. They require lots of reading about first.
Any questions feel free to PM. I know how maddening it can be.
(edited part) Wanted to add not unusual to get 250,000- 350,000 miles on those engines. I didn't believe it either at first.
2003 Majestic 23P... Northwest travel machine
2013 Arctic Fox 25W... Wife "doll house" for longer snowbird trips
2001 "The Mighty Dodge"... tow vehicle for "doll house"