Yeah Roadkill, install one engine first, then the second.
No matter which two engines you install, you will absolutely LOVE!! the extra power the second engine contributes.
My B.O.B. trailer had two pivots; the side-to-side pivot is at a 75-degree tilt forward. It is located less than one inch from the edge of the rear fender.
The up-and-down pivot is at the rear axle fork.