If there was nothing in the manual, nothing printed on a sticker or into the metal of the hitch for weight ratings. I would attempt a phone call to keystone and get what they claim is the max. wt.
2013 24RKSWE (27ft TT) Cougar 1/2 ton series
2013 Ford F350 4x4 CC 6.7 engine, 8 ft bed 3.55 rear end lariat package
Retired from Oregon State Police in 2011 than worked another 9.5 years as a small town traffic cop:
As of 05-2020, I am all done with 39 years total police work. No more uniforms for me.