[FrankJ]

The 501C has an obligation to sure that the funds under its control are used for tax exempt purposes & track them in an auditable manner. While what you propose is not "illegal", I can see why they would have a problem with that. They have a lot of freedom on how that is done. It sounds like the ASB has thought through its policy and is probably set in its ways. If it is associated a school, it might well have policies dictated by the school. They probably have a limited ability to deal with different rules for different clubs. Definitely worthwhile to talk to them, but do not be surprised if the answer is 'we have to follow our policy". You might be able to work out a "petty cash" fund that would be refilled as receipts are turned in. Or maybe a budget they can preapprove.
The advantage of having your own 501C is they can more nimble in the way they handle funds.