First of all i have a Kipor 3500 gen , I would like to mount it on our 17 lib dlux , question is where rear bumper or on the toung , its weight is 150 -200 lbs . has any one dunn this i know i will add a WDH to even the wight out . thanks

I don't think I'd hang in on the rear bumper. 150/200lbs is too much weigh on the rear and could upset your weight ratio, front to back, and cause the trailer to be unstable going down the road resulting in swaying. If you feel it needs to be mounted permenately, I'd figure out a way to mount it to the tong. My suggestion, however, is to not mount something that heavy anywhere on a light-weight trailer.

It seems that that is way more generator than you need to run the air conditioner.

I am aware of a member here who has mounted a generator of a similar size on his trailer's tongue... and it involved lengthening the tongue.
Kurt & Ann K.
I haven't seen him online recently... but maybe you could send him an email?

A 3500 watt genset is plenty of power, but it's weight is a bit much. If you have to put it on the trailer, you'll have to stow it as close to the axle and a low as you can, or it will greatly effect your trailers handling.

Your best choice (and IMHO) would be to stow it in your toad instead. It's a much safer choice. Mine goes in the back bed of my pickup.
ConwayBob