Let's see some pics....I'm a fifth wheel junkie ?Take a look at the Anderson Ultimate. I have an 18 Pro4X diesel and tow a Cougar 359MBI with it using my Anderson hitch. I love this hitch for its ease of use, ability to take in and out by myself (weighs 35 lbs), and the testing Anderson puts into it's products. It is greaseless and allows for off-camber hitching and un-hitching (some parks are fairly uneven) with no drama.
As for the Grand Design, I wish I had gone with them over Keystone as I live in mine. Their quality is top notch and when I am able I will switch over. Good luck.