I think you are totally fine...I think $100 a day with some grocery supplements (snacks for room and park, water bottle, and perhaps some quick breakfasts..$200max) you will be totally fine.
We did Chef Mickey too (I hope you have a late PS -we used it like a brunch, and it was FANTASTIC), we also ate at the Beirgarten, various counter service and the POR food court. We split a few meals (eg the kids and I would split a adult breakfast at POR and I would get an extra side of meat..the 3 of us had a great meal less than $10). I did do the Double Burger at Cosmic Ray's, and got the extra bun. You can really make a big dent in the price that way, but i did not make a salad out of the condiments. The only thing I put on the CC was HDDR, but that was planned. Our total at checkout was $1000. We did not cut back on too much. The kids (2) both got to pick out 2 sov's each plus they each got 4 pins each...so I think that total was around $90. that was on our room charge along with all food except HDDR.
So I would say ...YES you have more than enough. $1300 + some meals covered...is just over $54 dollars a day per person. I don't think a 4yo can eat that much

If you still are having any doubts check out the menus at allears, and see the best place to use your voucher, and the best places to spend your money. Don't forget about Trail's End...plenty of raves about that!!!
I hope you have a great time!!! Let me know how you did. My boys at 5 yo loved sandwich bags of trail mix, a bagel, granola bar, and M&M's on line for rides. We brought a Brita water bottle, which was great...we only had soda with our meals, and bagels, peanut butter, mini muffins, fruit, and other snacks were a big hit in the room.
I hope you did mention your sons B-Day when booking your PS, and don't forget to stop at Town Hall for his pin!!
