Yep, only thing I can think of to add is to have a photo of the rack to show him...maybe with some live product displays (one of the NFL mixes for example). You said the location is tiny, so if he worries about room you can always start out with a 3 way rack, which is really only an inch or two wider than the base of a pipe stand...in other words, tell him it will fit where your charity head is now. He probably does not want the guilt and/or bother to kick out the other charity units, so you might also say that you have another spot to put your charity head in...so he won't think he is hurting your charity either.
I would then clean and refill the rack every week (if practical, say only 5 or 10 minute extra drive), but wait to pay the first commission until probably week five so that when you do the first payment will be significant...and of course make sure he is there to receive it. The first few times you come back, you should go up to him first and just tell him you are there to clean and restock...that you usually count only once a month. When he gets a good amount of commission, he may be more willing to let you expand.
Good luck, Jerry