I had mentioned before about making an under quilt from a Military Surplus Th insulate Poncho liner.
This site has something very similar to what I envisioned. #12 as you scroll down.
I'm wondering if you would even need a pad IF this would keep the wind off you and allow you to vent excess heat/moisture if needed.
Some of the ideas would seem like they'd move around unless you lay perfectly flat

How about night time bathroom needs?
Seems like trying to wrestle yourself out of a top load hammock could result in a face plant if not careful.
I guess you can work that out if it becomes an issue

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DD
I think what you are describing is one of the combinations I use for the colder summer nights (35-40°) but you are using better (= warmer) garments.  Does your jacket have a hood? I really like a hood on the colder nights.  As you mentioned getting in and out of a bag is a hassle but using a bag as a blanket with a foot box makes a nice cover?  With the rest of the garments you have a light summer bag would be nice to use as a blanket with a foot box.