If you're weary of toting your photo gear in the field, a wheeled cart may be the answer. Various forms of carts intended for other purposes have been proposed in discussions of the problem on the Internet Usenet News groups including game carts (aimed at hunters needing to haul big game out of the field), and baby jogging carriages (aimed at parents who want to take junior on jogs with them), among others. The problem with these solutions is they are large and usually quite expensive - typically over $200 for a well-constructed example. Definitely overkill - in terms of capacity, weight, and cost.
Thinking about adapting a golf bag pull cart, I ran across the Model TS4060 Stow-A-Cart made by Tartan Sports. The unit is well-constructed, and sufficient to carry 50-75 pounds of gear, weighs about 7 pounds, and folds to a compact size.
By placing the shoulder straps on a LowePro Photo Trekker Classic over the upper golf-bag support on the cart, the backpack's straps
themselves can be used to lash the backpack securely to the cart. Adding a small bag between the wheels of the cart, a tripod can be supported on the underside of the cart, with the tripod head being strapped to the upper part of the cart's handle, just below the extension.
In this configuration, the weight of the camera pack and the tripod balance well, thus requiring only minimal downward pressure on the handle to raise the foot of the cart for travel. The extended wheels provide a wide stance (27" across) for the cart, and the wide surface of the wheels should provide better support in soft dirt and sand than a cart with bicycle-style wheels. The wheel bearings are sealed, and the wheels release quickly from the cart frame for storage.
You may have noticed all that empty space below the LowePro pack. If you're the type of photographer who just can resist overpacking,
there's just enough room to lash a Tamrac (or similar) airline-sized wheeled cart above the foot of the cart, as shown here. The added weight of the second bag below the pivot point, however, makes the configuration less comfortable to pull, but is certainly better than carrying the bags yourself.
Possible additional modifications include adding some form of light-weight lateral support beneath the bags to provide additional resistance to the bag twisting on the narrow center bar of the cart. Although cross-lashing the bag at the upper golf-bag support seems to prevent twisting, the additional lateral support might prove convenient in the field. The trick would be to design it in such a was as not to diminish the compactness of the folded cart.