There are many threads here at BP.NET dealing with gear. IMHO it is much better than the FB groups.
It was so cute last year getting our gear together. My wife and I laid out all of her clothes to take.
Other than cycling jerseys (Wheatons in Kalispell) and baggie shorts, we compared piles.
I've done it before and have it finely tuned. My first year was an absolute panic.
Then we weighed piles of clothes. Then she tried to bargain. She finally agreed that she didn't need a nightgown. And she shed weight from there.
Our target was to hit Kallispell in 5 days or so, buy new clothes, ship the bike back and be tourists for a couple of days.
When we did initial loadouts on our bike, we had a lot of room. The frame bag on Lolly, our tandem, is huge. But it all boiled down to weight.
Full loaded with water and gear, she came in at 90#