I think the best suggestion of all was to get a postage scale.

Here is what I found I could reduce easily at zero cost. The numbers don't show up well here, so here are the items I reduced. The total savings is 3,178 grams or 7.14 pounds.

This alone will get my pack weight from 43 to 36 pounds. For solo, I can reduce it another 4 pounds with a different tent and probably another pound with a new sleeping bag. Other odds and ends will probably save another pound, so it puts me at 30 pounds for a 4 day trip. As I'm real comfortable with 35 pounds, it puts a 7 day trip easily in reach.

Added: I just realized I'm the water mule, so I can reduce by another 4 bottles of water which is another 7 pounds. That would put me at 23 pounds for a 4 day trip. Now to actually pack a pack and see if it works out. (Is that ultralight yet?)

Full fuel bottle
Half fuel

underwear 2 pr
Commando

Fleece
Long johns

Lots of extra food
Exact food for 4 days

Pots
Not used

Parachute cord
Reduce parachute cord by half

5 pens I found in my pack
1 pencil

Small tube toothpaste
1/2 small tube

4 spare lighters
2 spare lighters

Backup flashlight
Smaller backup

Squirt tops for bottles x 5 bottles
Non Squirt top

Plastic coffee cup
No coffeecup

Toothbrush
smaller toothbrush

2 small camp towels
2 half small camp towels

Full roll Toilet paper
Half roll Toilet paper

Pillow case to hang food
Plastic bag to hang food