Disney is cracking down on all offsite golf cart providers. None can honestly say they will deliver to the Fort on every rental.
Folks sometime can get a cart without a pickup when, for example, I'm leaving the Fort the same day you are arriving. In those cases, the vendor MIGHT simply make arrangements between the two of you (the pickup and the following drop off) that will not require going offsite. But obviously you never know who's renting immediately before your arrival until, well, just before you arrive. So you can't count on that.
Kenny is more responsive to telephone calls and people have reported better luck if you try him in the morning (like 8-10am) but you have to be persistent. His number is on his website.
You might ask any vendor if you can meet them off the Fort and you drive their vehicle in. For example, take a bus to Downtown Disney. Have them meet you there (they will have the trailer with them). Ask if you can drive their vehicle into the Fort (you will use your Magic Band or KTTW card to enter the front gate). Obviously this will take an exchange of cell phone numbers to work. Do it all in reverse for a pickup.
Disney's intent is to make it as inconvenient as possible for guests using offsite vendors who rent at a lower cost in order to try to reestablish their monopoly on the Fort property at confiscatory rates.
So you can:
1. Pay the Man
2. Scramble to save some $$$
3. Do without
Bama Ed
PS - oh, gia2012, I saw a post you made last year about Fort cabins that are near campsites and how to arrange it. Unfortunately you didn't get a complete answer. For folks that want a cabin and a campsite close to each other, we recommend loop 2100 for the cabin and 1100 for the campsite. These loops are adjacent. Each party make a reservation separately requesting the recommended loop. Then EXCHANGE reservation numbers and call WDW reservations back and have that other ressie number added as a note to your reservation. That is called "linking reservations" (I want to be near them and they want to be near me). Those two loops are back to back and you could throw a tbone steak from the back of a campsite in 1100 onto the deck of a cabin in 2100. They are that close. So linking reservations will get you there. And when you check in (both of you) make sure this is actually implemented.