In a word: dicey.
Getting your client's permission is probably the easier side of things [although it's absolutely essential].
I'd suggest a very polite, open conversation -- this probably isn't worth jeopardizing a job over. They should be amending your non-compete to reflect your freelance work given their desire to incorporate it and provide you with with an agreement that, should you leave the company on any terms, the logos will be taken down. Basically you want to show them that you're happy to help the organization but think like a business manager here and are concerned for the opinions of your clients, their brand and your own.