Can we come up with some effective ways to communicate what we have donated, which allow us to avoid the wrath of the egalitarian instinct?

Pull-based rather than push-based systems can help with this. That is, if I perceive myself as having looked up your donations, rather than perceiving you as having informed me of them, I'm less likely to perceive you as boasting. The example you give of donation drives reporting amounts takes advantage of this.

Making reporting the unmarked case can also help with this. If I expect everyone to report their charitable donations (for example, if it's mandatory), I'm less likely to perceive the fact that you reported your donations as boasting.

Indirection can also help with this. If a third party reports your donations, I'm less likely to perceive you as boasting. (The "wing-man" strategy for dating is similar to this.)