Like any used RV, give it a good going over especially looking for signs of any moisture damage (inside & out). Another area to check is the undercarriage and axles, look for signs of any impact damage because some TH owners tow their units off-road. Also check the integrity of the rear door/ramp.
Make sure the WDH weight rating will accommodate the TH's tongue and gross weights both loaded with/without the toys.
Here are Jayco's publicized spec's on the Octane ZX T29M:
Unloaded Vehicle Weight (lbs.) 7,720
Dry Hitch Weight (lbs.) 1,130
Gross Vehicle Weight (lbs.) 11,950
Cargo Carrying Capacity 4,250
Exterior Length 33'-7"
Exterior Height with A/C 146"
Interior Height (living area) 102"
Cargo area length 12'
Fresh Water Capacity, includes water heater (gals.) 112
Gray Wastewater Capacity (gals.) 35
Toilet/Black Wastewater Capacity (gals) 35
2016 GM 2500HD 6.0L/4.10
2005 Jayco Eagle 278FBS
Reese HP Dual Cam
Putnam Class V