Sleeping bag UQ?

[Trugracie]

I am having a camping trip here in the next week, and nights are supposed to get in the mid 40s.
I bought a 40deg sleeping bag, and was wondering if I should sow it doubled up, or single, and also how long.
I was thinking of making it 40"x40" out of a single layer of the sleeping bag. I was also thinking about doubling it up, but it just makes a massive roll, almost bigger than my regular sleeping bag.
Any ideas of how I can make it as small as possible, and still be warm without a CCF pad?

BTW, My hammock has the Nosee-um netting attached to it, and the bag can be put between netting and hammock.

[slowhike]

I think I would just use it as a single layer, & make it w/ the same method I used to turn a sleeping bag into an under quilt...
sew the perimeter of what you want to keep, then cut away the excess, but leaving about 2 or 3" to be folded & sewn as the hemmed edge.

You may want to try it at home, using the netting to hold it against the hammock. The netting may hold it to tight, compressing it, or to loose, leaving an air gap.
If so, just add loops for shock cord at the four corners & attach it to the hammock ends.
You'll need someone close to your weight to lay in the hammock while you check it out & make adjustments.

[slowhike]

Truegraci asked a few more questions by PM. I'm going to be away from the computer most of the day, so I'm posting most of my response here in hopes that he may get further exchange from others. He is new to hammocking but not camping, & is going camping soon & using his hammock outdoors for the first time. I hope he'll be able to come back telling us how warm & toasty he was!

On the size for an under quilt, I would make it about 3-5" shy of the width of the hammock you are using.
And for the length, I would probably make it as long as the sleeping bag will allow you, to protect both head & feet.
Some are using shorter UQs now w/ something like a pad to insulate the feet, but I get the impression that you are wanting to keep it simple for now, & there is some learning curve involved, so that's why I suggest the full length UQ.

As far as the single layer being warm enough, that will depend on how much loft the sleeping bag has to start with, the temperatures you use it in, & if it is properly suspended on the bottom of the hammock, that is not compressed or not hanging loose leaving an air gap between your occupied hammock & the under quilt.
I know you mentioned avoiding a pad, but personally, I always carry a ccf pad, even though I don't use it inside the hammock. It serves as a sit pad, a wind screen for my stove, & a back up layer of insulation if needed.
It could be added between your newly made underquilt & the outside of the hammock to add quite a few degrees of comfort.