dutch71 wrote:
Did any of you ever had to build such a thing?
The answer to this question is, "No." Everyone just takes the tailgate off and makes a compromise.
I understand your idea, similar to a "bed extender" which you can get at Harbor Freight for about $65.
https://www.harborfreight.com/truck-bed-extender-69650.htmlThe problem is no matter what precautions you take it will be impossible to prevent your tailgate from becoming damaged supporting it this way.
If you let it set on the support by gravity, every bump will cause the tailgate to hammer up and down on the support, denting it.
If you try to squeeze the tailgate between the support and the camper, the sheet metal will become creased from the support.
If you try to strap the tailgate to the support, vibration will rub the paint off EVEN if you put carpeting or other padding between.
There will always be some movement to contend with and any contact between the support and the tailgate will damage the tailgate.
The only way I can see it having a chance of working is if you design the support to reach around the ends of the tailgate and support it by the pins that the cables attach to. Now the design is no longer simple and convenient.