Sway Control

easiest way is with a tongue scale. since they cost money and most of us don't have them.......... you can use a bathroom scale and some wood to create mechanical advantage so as to not crush your bathroom scale. That said you should go to a scale and weight the whole rig loaded to camp otherwise yoy wont know what your tongue weight is a percentage of. fast and easy to weight at the scale. weight the truck then weight the truck with the trailer hooked up but the trailer wheels off the scale. the difference is tongue weight.

https://www.etrailer.com/faq-how-to-determine-trailer-tongue-weight.aspx