I have the same cart.
2nd year of ownership, upgraded the wheels, 20" bike tires with solid tubes. Much better ride and ability to roll over obstacles.
3rd year, welded expanded metal to the deckandmade some sheet metal wheelguards, same idea as the safety fence,only stouter and allows use of bungies/ ratchet straps to secure load.
4th year, added extension handles on both ends to make the cart longer and taller for more leverage and control. plus welded on some adjustable down tubes to act as skid brakes, work awesome going down hill, removable going up or flat landing.
This year making a trailering hitch system to attach to my KLR in case I can put the bike to use in the haul out.
I'll post some picks when I use it this year