New to 5th wheel with trailer idea

I am first wondering if my Mako is safe to add a hitch on. I have a buddy who is very good at welding and have the hitch already off a friends who never uses it. Where do I find what my trailer is rated for? I believe my Ranger UTV weighs about 900 lbs, trailer for ranger 1200lbs, dirt bike 200 lbs. After I find out if the trailer hitch and the Mako is ok with this, I want to make sure my truck is ok. I think it is but wanted a couple opinions.

I've added hitch receivers to all three of my 5ers. However they were custom fabed and welded to the trailers main frame rails and cross members. Pulled a 3400 lb bass boat for several years behind a 26' 5th wheel trailer with a '90 2500 chevy 5.7 215 hp/300 ft lbs engine and 4.10 gears. No issues.
Trailers don't have a rating to pull another trailer as in a double tow. All three of my trailers were out of warranty so myself and the fab shop looked at the trailers frames rails/cross members/out riggers/pin box mount and decided the trailers frame construction was ok for pulling another trailer.

I would add a rack to the second trailer for the kayaks. Gets them out of the wind.