My plan: I got a yard light timer that is rated for 1875 watts resistive, and has a water resistant housing.
I just got the cord for my truck (yay!), and what I would do is add an oil pan pad, while keeping the load under 1500 watts or so total.
Then I would figure out a proper amount of time through trial and error. Set the timer, plug in and go to bed.
2007 Dodge Ram 3500 SRW 4x4 with 6MT
2003 TDI Beetle
2002 TDI Beetle
currently parked - 1996 Dodge 2500 Cummins Turbodiesel
Custom cab, auto, 3.55 gears