I think you've made the PP meet it's match. TOO much TT for that truck. 40' is way long. I just don't get why some people have to get the biggest baddest trailer and then compromise on the truck. IMO I would've thought the PP or HA would've helped more. I know I towed 7300lbs @31' with an F150 with only a 145" WB using an HA and it was great. Really about as good as my 2500 and current 5th wheel.
But no way would I want to of towed 10,000lbs and 40'. Thats really 2500-3500 territory. The dry tongue weight is 1235lbs dry. Add 90lbs for two batteries, 50lbs for propane and another 100lb+ for stuff in the front and you're close to 1500lbs on the tongue.
I normally don't go all weight police but in this case I will. You are way way over your receiver rating. More than likely over the RAWR too. You're simply asking TOO much of your truck to be safe.