Simple... go into the G code that BobCAD creates, delete or change the couple lines you don't like, and run the part. A little manual intervention will get the job done. Spending hours getting your software to do what you want doesn't. Especially when all we're talking about is a two pass slot.
Came across this issue a couple of years ago with another Poster, you can do it using the "3 Axis Wireframe" option, just draw the geometry you want to cut which in your case amounts to 3 lines and then just have the feature follow the lines.
Small downside is that when it reaches the end of the first level cut it only goes down to the next level at Feed rate not rapid, you could easily put a G0 @ line 90 and back to G1 @ line 100 in the code, if you can live with that then give it a try
You don`t say what version of BobCAD you are using so I don`t know if you will be able to open the attached file but here it is anyway, done in V28.
Sample code :-
(FIRST CUT - FIRST TOOL)
(Machine Setup - 1 3D Engrave Rough)
(FEATURE 3 AXIS WIREFRAME)