The tanks are in front of the axles. The 2 hoses in teamfours picture are the overflow (not valve) is attached to the top of the fresh water tank and the low point drain (with valve) attached to the bottom of the fresh water tank. the weight of the 40 gal of water when the fresh tank is full equals approx 320 lbs. (water is 8.33 lbs/gal) On a 7000 lb trailer it isn't really that significant especially since it's near the axles.
I would suggest adjusting the WD hitch. I would try moving the hitch points toward the front
Mark, Vicki, & Scout THE dog
2015 Hemisphere 282RK
2010 F250 Super Duty
1992 Goldwing Aspencade