Welcome to the forum Rob.
Just some points on your issues.
If the truck has a suspension lift their not all created equal even for a one ton truck. Some were made for show and no go.
Do your home work if the lift is up to carrying heavy loads on a regular basis.
The 326 RDS Cougar website shows a 13' 2" height. Minimum fed bridge height is 13' 6 " on interstate and NNS roads. Other smaller state hiways and roads and covers over fueling stations can be less. JMO but a trailer that tall isn't a good match for that much lift. Your call there.
For short bed trucks and a extended pin box I've used a 4"-5" clearance on a couple of 5th wheel trailer. Long beds I would want a 5"-6" minimum. Most folks with lifted trucks usually pull toy haulers off road and need even more clearance.