Next you will need a ground sheet made of any sort of waterproof material. You can buy ground sheets from a camping store, use heavy weight plastic or builder's plastic or an old shower curtain. Your ground sheet will need to be about 2 metres x 1 metre, a little longer and wider than your sleeping bag when it is rolled out.
I found that having the builders plastic really makes crinkles and russling sounds at night. Also the builders plastic is 'slippery'. The ground sheets that appear to be made of the matted plastic wear down slowly but you do not slip down wards so many times. As things should have at least two uses on camp have you considered how the ground sheet itself would be protected from ripping if you had to use it for an emergency shelter?
When you are sleeping, your ground sheet protects your sleeping bag and sleeping mat or air mattress from moisture and protect you from the cold. The warmth of your body draws the dampness up out of the ground and the underneath of the ground sheet will be quite wet in the morning even if the ground appeared dry when you laid the ground sheet down.
During the day your ground sheet will form the waterproof outer layer of your bedroll.
