First of all, If your FW has the rounded nose, you won't need a sliding hitch.
GM has the longest distance from rear axle center, to back of cab. That, and the fact that most newer FWs have rounded front corners, that are purpose designed to tow with a 6.5 bed truck. If you think you still have to have a slider, for that once every five years, that you get in an extreme backup, then get the Patriot manual slider.
Since 99, I've been towing a FWs with Fords, that have 2"s less distance from axle center to cab than your GM, and never come close to hitting cab.
A Patriot non-slider would be a good choice for you, and they are adjustable ahead/back, very easily.
Jerry