How much help is too much?

Hi, my 24 year old son has been experiencing some mental health challenges. We are currently waiting on appointments for a comprehensive psychiatric assessment - after several different medications have been unsuccessful. His mental health is quite episodic. He is currently on a job seeker payment with a medical exemption saying he doesn't need to be applying for jobs. He has a causal job with an amazing boss - some weeks he doesn't manage to make it in to work at all, others he manages four shifts etc. His government payment changes according to how much he has earnt that week. The way his pay cycle works it sometimes means he has a week with very little money - his government payment is fortnightly and if he had a good fortnight at work he gets very little government money but then if he has a setback and can't make it to work he gets no wage and it can take a week or two for the government money to catch up - leaving him with no money. My husband and I help out when we can but are reluctant to keep doing this - first, because it puts us under extra financial strain but also because I fear we are making him too dependant on us. He lives with a mate and often can't afford his rent - he is able to move home but his independence is extremely important to him and moving back home actually makes his mental state worse as he becomes despondent and his self esteem plummets. We are trying to help him set up his budget with a reserve fund that he can draw on during those weeks he has no pay but his impulse control is not great and if he has money he just spends it - eg he'll have no money for petrol or rent but we will notice he has new shoes etc. We have told him we can help with his budgeting but can't continue to give him money and "bail him out". 

My question is, when it comes to his finances, how much support is too much? We had an idea to set up an account that requires joint authorisation for withdrawals - all his wages and government money would go in here - his rent and other bills will be debited form here and he will receive a weekly amount into his spending account for extras - entertainment etc. He will have full control over his spending account but any money withdrawn from the reserve account will need either myself or my husband to approve it. He is keen for this arrangement, the money belongs to him and anytime he decides he no longer wants our authority attached to the account we will remove ourselves no questions asked. Is this to "controlling"?? Is it making him too dependent? His psychologist told us he needed a bit of "benign neglect" when we were paying his rent too often etc which is why we are stopping that - I don't want to just completely withdraw all our support though and this seemed like a way we can support him to do things himself with a bit of extra guidance until he is on his feet. Is this mollycoddling or worse, coercive control?