It was a tight fit but we've got our 72" tub dry fit into the alcove. According to Kohler's installation instuctions, it can either be set in mortar or installed using construction adhesive on the five "legs". With the close quarters and drain location, it would be much easier to skip the mortar and go with construction adhesive but, before we do, I'd like advice from the GW pros or experienced DIY'ers. Do you consider mortar a "must"?

Standing in it as it sits in place, there is very little if any flex and it is sitting level now.

It's now or never on the mortar, what would you do?