Charlie,
I can tell you right now there is no way you can pull a 4012 with your truck. I have a 3795 and I can not pull it with my F-350 with a 9 ft service body on it. Because the top of the bed is 62 inch high from ground to top of bed. When the truck shifts up and down left or right it will hit the under side of the trailer.You need at least 10 inchs between the top of the bed and under side of trailer. That is even more true on the toyhaulers seeing how you are likely to go off road like a field or dirt road ect.With that said also you said you have a Dodge Mega Cab. If it is not a Dually than your truck is to small to pull a 4012. We pull our 3795 with a 2006 Ford F-350 DRW 4x4,Tow package,4:30 rear and it is max out with our trailer.The trailer alone weighs in at 12300 lbs empty.The whole rig truck,trailer,two harleys,camping gear ( not that much gear),two adults,two kids,dog,cat,no water,2 full LPs,food,clothing, it weighed in on the ceritfied scales @ 24,426lbs The 4012 is bigger than the 3795 and the empty weight is more. A F-350 4 door tow boss max 5th wheel towing weigh is 18100 lbs,450 is 21,000 lbs,550 is 24000 lbs. I have been driving big trucks for many years (Fire trucks and tractor trailers) there is no way I would pull one of these rigs with less than a daully! With a lift kit it would be even worse!