There are some good pictures shown in the Collectors illistrated guide to the American Revolution. The pictures show all the nessesary details to make one. The sketch book 56 series on Rogers Rangers shows some basic pictures but no details. My wife made mine in about 4 hours. very simple for her. The one I chose was the double compartment model as used by the British. It is made of heavy canvas and holds a complete set of extra clothes as well as accessories. I water proofed the fabric with tent waterproofing. Some of the origianals were painted to make them waterproof.
Regardless of what was seen in LOTM, I believe that this style of pack was more of Revolutionary style than F&I. At least that is the vague recollection I have.....
A single pouch/modified haversack with shoulder straps may be more appropriate for the time period. However, haversacks seem to be more associated with military units rather than civilians. A clarification of your persona might help others to direct you to the proper style.