AutoCAD Inventor :: Can Frame Generator Skeleton Be Sheet Metal Parts

Up until now, for FG I've always created a part with just a sketch in it. I insert that in an assembly and use it as my frame generator driving part. Now, I've started creating a solid instead of just a sketch in the part and using its edges to attach frame members. Picture a cube. I really need to put sheet metal on the cube and have my frame on the outside of the sheet metal. I was setting up a parameter for the sheet metal thickness and offsetting the members in Frame Generator that parameter. Now, I've accidentally discovered that I can select the outside edge of the sheet metal part to attach my frame members to. Is that a valid workflow? If it is, its a bit of an epiphamy for me. Using a parameter in FG as an offset required me to edit each member with FG and update it to get the offset to use the current parameter value.