As you've pointed out, the main issue would be the association between these new "chakra donors" and the old "skinwastes". We'd need to destroy that association: figure out how to present the new demographic in a way that makes people interpret its members as "elevated civilians" rather than "failed ninja".
I don't think that would work. The comparison is too obvious, and too legitimate. Also, "elevated civilians" isn't exactly an unambiguous positive either - arming civilians with stuff that lets them credibly threaten ninja tends to provoke strategic panic and massacres. Piling on a bunch of wild new ideas would set off peoples' bullshit / fast-talk defenses. I'd say, keep it simple, and start by building off of stuff they wouldn't dare argue against. Something like:
"The Will of Fire is something we all partake in, and contribute to. We're not like Yagura's Mist, tangled up in paranoia and coercion. We've got Tsunade, who's the greatest mednin in the world, and such a badass that even Pain basically admitted she'd be able to beat him in a fair one-on-one duel. You think it's just a coincidence she spends so much time out there using her skills to benefit civilians? Given the world we live in, violence is necessary... but cooperation and mutual support are the true source of our lasting strengths.
"Now, obviously, cowardice and sloth are moral failings. The question is what to do about it. In Yagura's Mist, well, long story short they mostly tried to compel people to work harder, or trick them into informing on their neighbors. Buried that sort of problem pretty well, but didn't solve it. Forced behavior isn't virtuous any more than having a rock thrown at your head is weightlifting. We can do better. When someone's naturally weak, or injured, or busy with other things, training needs to start small, so they don't overdo it and end up worse off.
"Accordingly, we've discovered a new minimum-viable exercise of virtuous, supererogatory pursuit of the Will of Fire: trading away your own chakra to directly support other Leaf nin. This form of service will
never be compelled. Not even by the Hokage, short of the most desperate military or medical necessity - we're NOT like Yagura's Mist! Forcing it would defeat the whole point. Lord Goketsu tried that on one of his own people, as punishment for a very serious crime, but the whole situation was a fiasco start to finish.
"So, if you're a good Leaf nin, come and sell any chakra you have to spare, at fair market rates - and whenever you see someone waiting in line there who you'd previously dismissed as a skinwaste, reconsider that assessment. Just showing up and giving what they can is proof they're trying to become better, same as you. That's worth something."
