What model year Talon is it?
The Jayco web site (click on "Product Archives") will provide the GVWR of the TH model in question and you can size the WDH based on the GVWR (worst condition). The recommended loaded tongue weight should be 13% to 15% of the TH's loaded weight (extremely important with TH's).
One thing for sure, once you have your TV/TH under loaded conditions go to a CAT scale for a weigh-in, TH's are notorious for under-weighted tongues under loaded conditions. Loaded with water/fuel.., and with the toys located in the rear loaded tongue weights can be all over the map.
CAT scale how-to: http://www.jaycoowners.com/forums/f37/how-to-weigh-your-tv-tt-3871.html