My son has a 2018 GMC 2500 Dmax shortbed and uses a ancient old rusted 16K Reese manual slider. He bought the hitch used and slide part has never worked/nor needed. The hitch has been on 3 different shortbed 2500 GM trucks of his with two different 5th wheel trailers.
Short bed GM trucks have the longest CA (cab to rear axle) dimension than Ford or Ram. Now add the new gen trailers with a rounded/notched front corner profile eliminates the need for a sliding hitch.
The only hitch I'm aware that has the narrow hitch angle you mentioned is the Superglide.
My '97 16k manual slider will hook and unhook at any angle...even 90 degrees
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides