2012 FX4 - I haul a small off grid trailer - and some time when traveling I end up in places that I do not unhook the unit when I stop - so when this happens the tailgate will not go down as it runs in the spare tire , and should I remove the spare tire drops about two more inches it will hit then the tongue jack - moving the stuff is not an option as the tongue also has a battery box , and the 20 lbs LP cylinder. - I can always lengthen the tongue but that plays with my “ trying to keep the trailer as short as possible “ I’m currently 12 feet hitch included

i have looked at a fifth wheel tailgate and the cut out on it would allow for the gate to be lowered with the trailer attached but the back will just fill with dust mud and water when traveling so that kind of kills that idea - my tri fold cover and factory gate make a good seal against this issue - any ideas are welcomed

if your wondering why I need to get in the back - 12 volt fridge on one side , a food locker on the other side

 

Sounds like a trailer that short which meets all your criteria is not possible. So lengthen the tongue - problem solved.

 

as I don't really know what you mean by off grid trailer.
I'm assuming a back country camper maybe.
why not just tilt the gate back and lift it off set it out of the way until you need to move on.

 

It is backcountry trailer- I do agree lengthen the tongue - just trying to avoid that unlike a conventional setup this has skid bars , plates that go from about where the jack is to the axle
I have toyed with the idea of taking a fifth wheel gate , sealing it and then putting a piece in the cut out that hinges back in

 

ARE with walk in door.
https://www.4are.com/product/walkin/gallery.php

 

If moving the tongue is out of the question...

Get a fifth wheel tailgate made of square tubing. Mount the hard plastic sheeting of your choice to all but the fifth valley. Bolt some channel to the sides and valley for the fifth hitch to hold a 3/8" sheet of plastic, wood... whatever. The bed cover or cap will hold the piece in place when closed. When opened, you can grab the piece and pull it out.

 

Give this site a look see. I'm thinking about one for my trailer.
http://jack-e-up.com/

 

Notching the t/g isn't really a solution, unless you can see the future, and you'll NEVER need to open the t/g when the trailer is out-of-line with the truck. Even lengthening the tongue will require more than JUST enough. The only true solution is to remove the interference from the trailer neck.

 

If by "small" you mean under 4000lbs so fairly low tongue weight there are many hitch extenders and extra length draw bars out there. Depends on how much room you need to clear. Reese makes an 18" hitch extender rated for 400lbs tongue weight and 4000lb GTW, under $100. Etrailer, Amazon, etc. Other sizes as well.
https://www.etrailer.com/dept-pg-Hit...nch_Hitch.aspx

 

Keep in mind, all hitch extender are torque multipliers. That extender with 400lbs on it could be placing a 1000lb load on the hitch receiver! If the torque multiplies out over the WC tongue rating of the hitch, gotta put a WDH on it. If it goes past the WD tongue rating, don't risk it.