too much emphasis on lists and spreadsheets and weights.......those are all great,
but try it the old-fangled way.

unless i missed something here............nobody said "why not pack all your crap
into your panniers, load up your bike, and go for a spin."

how does your bike handle on a smooth surface, on a rough road, up and down
hills? how's it feel after 3 hours? maybe try an overnighter?

while still loaded.......can you pick up your bike? can you carry it up a flight of
stairs? three flights of stairs? how much trouble is it to lift all your stuff over
a 3- or 4-foot fence? or cross a drainage ditch?

if traveling by air, can you fit everything into one box, one checked bag, and a carry
on? how bulky is everything? will it all fit on one luggage cart?
[*with bike box horizontal, cart won't fit into most airport elevators*]

now ask yourself:

do i NEED 6 spare tubes?
do i need that short-wave radio?
do i need that laptop computer?
do i need that 250mm zoom lens?
do i need 4 pairs of cycling socks?
do i need...............