I need some advice and thought I would post here due to the respect I have for the members of the forum and the vast experience.

I will be camping (trailer, not backpacking) in Wisconsin in the chilly month of February with a Scout Troop.
I am specifically looking for real world experience with a sleeping setup. I have searched online and have found conflicting suggestions concerning using a cot. I have a cot and prefer it to the ground. I have read that using a cot will allow the cold air around you and can cause greater heat loss. I have also read that using a cot gets you of the cold ground.
Any thoughts on using a cot?

Back round: My sleeping bag is old and probably rated to 35 degrees F or so. I have a fleece bag that I put inside along with water bottles filled with water slightly below boiling. I used this setup down to 10 degrees F and it worked well. Underneath, I used an inexpensive blue form ground pad along with a carpet remnant and an army surplus wool blanket. I also changed into clean night clothes with wool/polyester socks along with a buff over my neck and with a wool/polyester hat.

Buying a new sleeping bag is off the table because I bought my son a nice bag so he can stay warm with little effort (compared to my setup).

Any other tips?

Thanks in advance for your time and input.

Assistant Scoutmaster and Cubmaster Dave