Look at my signature. Our Cougar is 6500 empty with a GVWR of 9900. So a little less than the trailer you are considering
Our truck has a 6.0L gas engine, 4.10 axles and a 6 speed auto trans.
In hilly or mountainous terrain I would not want much more trailer weight or 3.xx gears. If most of my driving was on flatter roads then 3.73 axles would do the job.
But we live in the White Mountains of NH and nothing is flat. 4.10 gears for us.
You are coming from a truck camper that may have been heavy but now you also have to overcome the rolling resistance of 4 trailer tires too.
I think that with your current setup your trans will be dropping into 2nd on many hills. Our previous truck with a 4 speed tranny was doing it and it was tiring to drive like that.