Tow vehicle Information

I have a 6 cylinder Honda Passport (2001). I do not understand the technical language regarding torque and rpm etc. but I want to be sure I can safely tow a TM without going over the weight limits. The car owners manual says the trailer wt and cargo load should not exceed 4,5oo# and the gross combined wt rating is 8700#. I thought it was as easy as picking the unloaded trailer weight, adding in the optional wt (lp gas, water,clothes,food)
or maybe allowing 1,000 pounds lea way for those extras., and essentially finding a trailer whose unloaded weight was less than 3,500#...when I ask the RV dealer, they say, to call the Honda manufacturer. Could someone out there tell me what information I need to ask the Honda people about my car to be able to determine what size TM travel trailer I can tow? The more books and info I read on this the more complicated it seems to become! I am sure I am not alone!! Right now, the TM use is just for one, me. But I like the 2720 SD model. I need to use this for intermittent housing ( 3 mos at a time) and for traveling. What type of climate/ weather conditions is the TM livable?? Will pipes burst in a freeze? I appreciate any input! S.A.