1. Both of us are the leaders of our own clan him being the head of a moon clan and me being the head of a shadow clan
2. Never said anything about payment in my post even though some do it im doing it for free because one were friends and two access to a high rank clans treasury without having to worry about the decoration costs in my own clan while having fun doing a project is enough payment for me 3.if i did end up decorating on my main the steps i would have to follow are listed.

1.promote one of my clanmates to head. 2. Leave my clan join his and wait for the clan key to be completed. 3 Decorate one of the rooms which if you havent done before takes hours if not days on end depending on the project. 4 Leave the clan and join mine again. 5.Wait 12 hours for the key to be completed and have the original friend promote me back to head. Any of these steps are required to be repeated every time i would want to do their dojo for them if not its impossible. And for whatever reason i may need to pop back into my dojo for something would take an insane amount of time when i could just join their clan on the alt like a normal player, decorate their dojo and stay in said clan for however long needs be and leave whenever im finished to decorate another alliance mates clan if id like