Hi guys, does the elite HK droid ability of 'figures do not block line of sight for your attacks' work on large or massive models? I was thinking of using a Bantha as a moving wall to hide behind, as i could shoot at enemies in front of it, while my guys are safely hidden in cover. Plus i could heal my Bantha wall from behind it too! Is this an actual idea that may work?

Yes.

The ability does not specify small figures, so 'figures do not block line of sight for your attacks' works for all figures.