You will have trailer tongue weight and added payload (scooter) on the rear axle and tires.
That might be a weight rating issue if you are running 'P' rated tires .
You will need to know the rear axle rating as well .
Check videos on 'how to set up a WD hitch' on youtube or at e-trailer.
They show you how to take correct measurements of your trailer and the TV (tow vehicle). You should do this with with all your stuff loaded up incl. the scooter . Don't forget, you will adding passenger and driver weight.
Once you do that, you might see that weight has been removed off the front axle of your TV and you might not like the way it handles decreasing vehicle control.
Both the TT and the TV should ride level. It might be time for you to buy a WD hitch.
Go to a scale and weigh everything (learn how to do that axle by axle , there are many tutorials on the subject).
I'll bet your tongue weight is more than 250# on a 21 TT . I think you might be surprised when you go to a scale. MY tongue weight on my 5x12 utility trailer is 250#. I use my own tongue weight scale to measure weights.