In Volume 2 of Horace Kepharts Camping and Woodcraft (1917) a featherweight kit designed by Owen G. Williams and marketed by J. Langdon & Sons, Duke St., Liverpool is listed.
40 oz "Featherweight" tent complete
15 oz Ground sheet and pegs for same
20 oz "Comfy" sleeping (eiderdown)
02 oz Compact brush and comb and mirror
02 oz Japanese rubbered air cushion
15 oz "Compleat" cooking outfit and stove
02 oz Aluminum knife, fork and spoon
03 oz 1/4 pint aluminum flask and egg cup
05 oz Enamelled cup, plate, and mop
06 oz Canvas bucket and wash basin 02 oz Pole clips and candle holder
Total weight: 7 lbs.
Not bad for eighty years ago.
Another list is given, this one by T. H. Holding
13 oz Tent
15 oz Poles (3)
10 oz Pegs
10 oz Ground sheet
08 oz Ground "blanket"
20 oz Down quilt
16 oz Cooking kit
Total weight: 6 lbs.
It seems as though ultralight backpacking has a long history.