Re-evaluate your trip and why you need a food drop resupply. Although carrying 10+ days food may slow you down a bit, after half is eaten, you can do more miles. I have done 14 day trips without resupply. If you prefer lighter pack and going fast on the entire trip, then just build in a day to go to a trailhead or town for resupply. Horse packers generally are not allowed to just drop a resupply; they may be required to actually meet you, and most would not simply drop off food even if it was legal. Resupplies require precise trip planning and are expensive. I would rather have more flexibility and just walk out when needed or carry more food.