How much clearance to you have with the 18? I have a shortbed truck so i need more room. I guess it will depend on the toungue length on the travel trailer.
BTW: Nice set up
I just do clear the TT. Also note mine slants back some as well. Like you figure every TT is different, but most have 4' tongues.
I have jacknifed it to see if it clears and I have a few inches, so I still watch it on unlevel surfaces. Pulling forward is no problem, I can do that without the extension. I have an electric jack that will not clear the beavertail without the extension (I can raise the center section if I'm only moving a little piece). Also remember you may need to extend your safety chains and possibly your power cable with the extension. I only needed chain extensions.
For me it's the best setup. The 350 handles the loads fine, not sure how a short bed would work, but your truck should be even lighter than mine (I weigh 7500 lb empty). My TT tows at 22' and has a queen bed rear slide so it camps at 26' (Around 7500 GVWR, I think). I used to have a 30' 5th wheel and towed a 10' tilt behind the 5th. That lead to some white knuckles and rolled a tire off the rim once on a bad section of road. Just picture playing crack the whip with trailers.
I also used to tow an ultra-light 5th wheel with a Tundra which has reduced clearance between the cab and camper. That may be where I learned to go really slow when backing and I try to avoid backing altogether when possible.
One other thing to look for is the ground clearance of the TT. I like mine a little higher for primitive camping. If you need to modify it, you can look into and axle flip or bigger tires. Mine came with drop axles originally, but the PO put on straight axles which raised the height about 5 inches, which is just enough for me.
