Flat

Just use the factory jack. Used it on loaded truck, loaded flat bed trailer, among other things. Only time I can remember changing a tire with a bottle jack was on the road when my single axle dump was overloaded with 11 tons in the bed. The 8-ton bottle jack said that was about all it was going to pick up but did get the job done.

Besides, I don't really have the room to carry an extra bottle jack. Space is all taken up as it is and I'm already heavy enough.