You need to go to a scale and get some real numbers if you really want to fix this and not take a poke in the dark.
Load it as you will for camping, trying to get more weight up front to get your Tongue Weight at least to 10% of your trailers actual weight, preferably closer to 13%-15%.
Once you know your in the range on the tongue weight, Measure your fender heights and read the sticky on PROPERLY adjusting your W/D setup and do so.
Then use your friction sway control and see if it does the job or if you need to add a second one or get a better system.
I'm going to bet, if you do the above, you won't have to spend a dime more and will get it corrected.
If you guess and don't properly adjust, your just asking for troubles. Safety is no place to gamble when you will likely have friends or family with you when your towing your trailer.