Ahhh the woobie. That was my sleeping bag; double the fun when wrapped in a poncho when wet times rolled around. No need for a bulky sleeping bag but then again, I made my time in warm spots....unlike my brethren in the cold areas of the world...my sleeping was done in the hot spots of central and south america. 10th group brothers I know....I have no clue what cold is!!!
I did try out sleeping in a "bear suit" (for lack of technical name for that big brown suit for the cold). Once that bear suit got wet the fun was done.
Another fave was the field jacket liner...basically a woobie in jacket form. I still travel with a woobie today as a civilian. It is part of my packing list...never leave home without it!