Need advice

That 5er has an 8,750# GVWR and a dry 1,300 pin weight.
If the F150 is an EB Max/Max, if so should be a good match.

Normally, I'd say that 100K miles isn't all that bad, but it seems as if this truck is undersized for the FW, so it could probably be considered to have even more miles/wear on it than if it was a F-250 say.

Of course, if the truck and trailer were well maintained over the first half of their lives, and you also keep things well maintained, it isn't unreasonable for you to get the years that you want from it. There are lots of RVs with a lot more miles and years than that!

Look around a bit more, checking out similar units, to see if you are getting as good a deal as you can, but remember that sometimes the deal that is "too good to be true"...IS!!

The Jayco is now about 6 years old. Another 6-10 years is not out of the question as long as you regularly take care of it, inside and out. The roof can be a weak spot and should be cleaned regularly and repaired quickly if you discover any holes in it or if the caulking needs repair. The suspension, brakes, bearings, and tires should also be checked and serviced when necessary. Interior items like the water heater, furnace, fridge, and water pump are other likely items that can pop up on you, but those things can go even on a fairly new RV.

My Cardinal is now 13 years old. I was considering selling it this summer. I looked hard for a good used 5th wheel between 2008 & 2012. I honestly didn't find anything within driving distance from home that I thought was a better camper for the money than the one we already had. I know the condition of everything in it and regularly wash it and take care of any issues ASAP. We'll pull it down to Florida again this winter. So you can see that if you take care of your unit it will last a long time.

Personally I'm a little iffy about the F150. I'm not sure that it's large enough for the towing package. If you're only using it to pull your camper locally and it's a great deal then maybe it's worth it, but it's not a long-distance towing machine. Regardless of what the seller says I'd try to get a better handle on what the pin weight capabilities of the F150 are. It just doesn't sound like a good fit to me.