Try this, find a cat scale pull just the front tires of the TV up on the scale with the rear tires off the scale. Write that number down. Then disconnect the rear trailer and write that number down. Now disconnect the TT unhooking the WD and jacking the tongue completely off the hitch.
The first number is your tongue weight with the rear trailer connected, the second number is your RV tongue weight. By doing it this you now know the actual weights as it reflects to your TV.
Now you should weight each trailer to get the actual weight as loaded for a trip (load it the way you normally would for a trip).
If your TW does not meet the 15% requirement then move some weight around inside the TT until you get there.
I would also upgrade your tires to E load rated tires for the added sidewall strength.
Don