Sketch plane-how to force a new one

Need help? We are here.
1

I’m modeling a trailer frame, just a rectangle, with sides
that are extruded tubes from a rectangle with a wall with thickness.

I draw one profile, extrude it, to form the left side, fine.
I copy this first body, move it to size, fine.
For the front side, I draw my profile on the end of the
left side, and extrude it to form the front side.

This becomes a body that includes the left side AND the
front side.

I want to select the front side, copy it, and move it to
form the back/top side.

I seems if I could make the front profile on a new sketch plane,
it would separate the new body into a separate body.

There are other ways to draw this, but is there a way to
separate the sketch plane into a new sketch plane?

Like some sort of explode feature?

Thanks.

2

I guess it’s simple to draw the profile on a plane,
and move the extrusion, then copy it.

3

Any planar surface can be used as a sketch plane, including body faces and construction planes.