I have used a half inflated neoair with a sportsmans blanket (mylar backed with nylon) for side breeze protection with good success... no slippage, good coverage, warm to slightly below freezing. Adding a cheap ccf when it's colder helps a lot (pads are easy to double and triple up - the R value can be increased quite simply).
Never bothered with a pad/UQ combo. the UQ is warmer when you are able to sink down into the hammock inside it... I would rather the quilt conform without any gaps. Winter yeti has sufficient loft to get me well below 20F. The colder it is, the more side coverage I want with the tarp, as cold breezes seem to creep in through the down - adding a breathable undercover and having a tarp guyed to the ground as a wind break helps.
I have heard people claim the NeoAir doesn't work below freezing... my experience differs quite a lot. You don't want to inflate it fully, even on the ground. Don't inflate any insulated pad fully in a hammock.