The DLH website is unclear - but Trader Sam's used to validate for 3 hours of parking, but only at Disneyland Hotel's self-parking. (If no one else chimes in, you might want to call DLH Guest Services to verify.)
If that doesn't work, there's a hackaround to limit it to $10. If you park in the Simba/DTD lot, you'll pay for the first hour ($10), but if you go to World of Disney and buy a $20 Disney gift card, they'll validate your parking for 3 additional hours. Then, you can use the gift card to pay for part of your Trader Sams bill (or anything else).