Duffel bags are not typically used for backpacking due to their lack of support and weight distribution compared to backpacks designed specifically for carrying heavy loads over long distances.

The ideal weight range for a backpacking pack is generally considered to be between 20 and 30 pounds, including food, water, and gear. This weight range allows for a comfortable and manageable load while still providing the necessary supplies for a successful trip.

Sunscreen is not typically considered an essential item for a backpacking first aid kit, as it is primarily used for sun protection rather than treating injuries or illnesses.

The recommended amount of water to carry per person per day on a backpacking trip is generally around 3 liters (100 ounces). This amount can vary depending on factors such as the weather, terrain, and level of exertion, but it is important to stay hydrated to avoid dehydration and other health risks.

Proximity to water is the most important factor to consider when choosing a campsite for backpacking, as it is essential for drinking, cooking, and cleaning. Other factors such as flat ground, shelter from wind, and scenic views are also important, but they are secondary to having access to a reliable water source.

The recommended way to store food while backpacking to prevent attracting wildlife is to use a bear canister. Bear canisters are airtight containers that are designed to keep food and other scented items safe from bears and other animals.

Distillation is not a common method for purifying water while backpacking due to the specialized equipment and energy requirements involved. Boiling, chemical treatment, and filtration are more practical and accessible methods for purifying water in the wilderness.

The recommended way to dispose of human waste while backpacking is to bury it in a cathole. A cathole is a small hole dug in the ground, typically 6-8 inches deep, where solid waste can be deposited and covered with soil. This method helps to minimize the impact on the environment and prevent the spread of disease.

Bivouac sacks are not as common as tents, tarps, and hammocks for backpacking due to their limited protection from the elements and lack of ventilation. They are typically used by experienced backpackers in dry and mild conditions.

The recommended way to pack a backpack for backpacking is to place the heaviest items at the top, closest to your back. This helps to distribute the weight more evenly and reduce strain on your shoulders and back.

Solar cookers are not as common as stoves, campfires, and rocket stoves for backpacking due to their reliance on sunlight and limited cooking capabilities. They are typically used in areas with abundant sunshine and for simple meals.

The recommended way to cross a river while backpacking is to wade across if the water is shallow and the current is not too strong. If the water is too deep or the current is too strong, it is best to use a rope and pulley system or build a bridge to cross safely.

Smartphones are not as reliable as maps, compasses, and GPS devices for navigation in the wilderness due to their dependence on battery power and cellular coverage. They can be useful as a backup navigation tool, but should not be relied upon as the primary means of navigation.

To prevent blisters while backpacking, it is important to wear broken-in boots, apply lubricant to feet, and use moleskin or bandages to protect areas prone to blisters. Taking breaks to rest and elevate feet can also help to prevent blisters.

Sleeping bags are not considered clothing layers for backpacking, as they are primarily used for insulation and warmth while sleeping. Base layers, mid layers, and outer layers are the three main types of clothing layers used for backpacking to regulate temperature and protect against the elements.