I have checked this site, was listed everytime I asked Google a question.  Most impressive.  anyway, I have an older Sundowner GN.  It was set to a dually when I first bought it.  I just bought  '06 dually with a 5th wheel hitch already installed.  Got the 5th wheel adapter.  the trailer sits high in the front.  I have a ramp on the trailer.

Found the thread in here where there is a GN hitch that goes between the rails on this 5th wheel hitch.  My husband claims the difference will not be much, that the nose will come down some but the tilt will still be about the same in the back because of the height of the GN hitch in the truck.  Noticed one said on here it was about 8 to 9'' off the bed of truck.

so I ask, do I have him (husband) cut off the hitch on trailer to make it come down with the 5th wheel hitch, jack up the trailer or make changes to use GN hitch between rails?

Thanks for your time....any advice would be appreciated.

got the info for fixing my aux. lighting problem here...putting female plug on battery box, my battery disconnect switch doesn't work.  thanks!

The coupler on your trailer is essentially a tube - one piece slides inside the other and is held in place with bolts.

It will take some work (spray bolts with WD40 and a pipe wrench) but you should be able to shorten the coupler pipe.

If you think the 5th wheel hitch is making the front of the trailer too high, measure from the 5th wheel plate to the bed of the truck. Then, have a friend who has a gooseneck hitch (not the underbed type) measure the same distance.
If your 5th wheel hitch is attached to rails in the bed of the truck, you can replace that assembly with a gooseneck hitch.

I suggest a visit to a trailer dealer (any kind - even utility trailers) to see what's possible.
Many times older GNs are not tall enough for 4x4 trucks which sit much higher off the ground.