how can i see 3/4 of a product in assembly design
Create a surface in one of your parts, so that this surface looks like a "L" in this region that you will cut out. The surface must be longer then all parts. Publish this surface and copy it with link in all parts that will be cutted. And now use the option split to cut every part, you must be defined in the partbody. Hide the surfaces and that is that.
Or poker al parts withe the same sketch.