I email a gear list to those scouts signed up for the trip, and any adults signed up. If they are totally new to the troop, I check with them to see what gear they need. I have some loaners of packs, and rain coats, but rarely use the rain coats. Each parent assembles and carries their own gear, and sleeps solo. We often have as many adults as scouts.
I plan an easy backpack in the fall, usually 3 miles one way to an point of interest, like a waterfall or a hot springs. Ater the 3 mile hike, kids say "that was easy, so now I think I could do a 5 miler."
The troop has backpacking tents. Our scouts have shown zero interest in cooking anything but freeze dried food, or UL gear. Many of the parents have revived their earlier backpacking interest, and often get new UL gear. I don't know if the parents or the scouts buy the upgraded equipment, but in our troop its likely the parents. The scouts see my and some leaders lightweight gear, so they are exposed to the idea of light weight, but they don't feel the need.
After 3 years of this program, we fielded a 9 scout group of scouts to go to Philmont, and every pack was under 25 pounds, for the 14-15 year olds. This group was basically the first graduating class of the backpacking program, starting them backpacking at 11 years as they entered the troop. Our older scouts from 3 years ago, had no interest, no skill, and no experience with backpacking, except they knew they hated it.