Finally some updates.
Today I installed the newly arrived equalizer WDH(Equal-i-zer 4-point Sway Control Hitch 1000LB). Driving on highway seems a bit better, but still not reach the comfortable towing experience. Can still feel a bit sway(especially when been passed, or sudden cross-wind), I had to concentrate on steering wheel when that happened. Also went to the CAT scale to get some numbers.
I recall it was mentioned that the adjustments of the WDH(even equalizer one) also takes a few tries. In my first attempt, hitch head was on a higher side( coupler 23 1/8, head was 24), which caused a raise in the middle. (Also that measurement seems suggest over-adjust - front well was even lower after WD engaged).
In the second attempt, I lower the head 1 bolt hole (also recalled BenK's suggestion above), removed one spacer washer, which made the head up/away from the TT a bit.
Below are the results of my second attempt.
Any further suggestions will be highly appreciated. Thank you
Calculation was following this instruction. https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25928885/gotomsg/25929827.cfm#25929827
