Best Practice for Mounting Tabs in Weldments?

I almost never work in weldments but I have a fixture frame I'm trying to model as a tubular structure. The frame will secure a motor and gear reducer plus a few accessories and a gauge panel. I have a good weldment model of the tubing and miters but now I need to add the mounting bosses and tabs (to be welded to the frame tubes). I'm not sure what the best way to go about this is. Should I model the tabs as separate parts in the context of an assembly? Or should I try to do them in the main weldment (as multi-body parts)? Some mounts need to have external references to the parts they are holding. How do people here with experience building welded frames do this?

Thanks

Peter~ 

SolidworksWeldments