FYI, in my instructions I accidentally listed the command as se but it should be sea, so I edited the post. You can use the se command to spawn the crate as well (if you look up the entityid) but it doesn't spawn it right next to the player so I recommend the sea command instead.
Unfortunately unless you create a patch for the game's code, there is not a way to spawn items at full durability that I'm aware of, as the game chooses a random durability when spawning loot. I mentioned this to you in a previous post already. You can add repair kits to the box if you want. I recommended the entity spawn because that way you can spawn it near the player as you wish and it works smoothly. The other solution is not as elegant, because there is not a command as far as I'm aware to give an item to a player, so you would have to give the box to yourself, teleport to the player, and then drop the box for them to allow them to pick it up. I'm not extremely familiar with the admin commands, though, so perhaps you know a command to directly give an item to a user. Furthermore, however, there is not a way to create a box that has items in it when you drop it, so you have to do a workaround where you create a box that has 1HP that deteriorates into a box that has the loot in it, so the player has to put the box on the floor, then hit it once, then they can open it. So for these two reasons (no command to give item, box has to be hit to deteriorate into a box that spawns the items), I recommend using the entity box that I created for you.