Oh, and also...
If you get a big can of oil (instead of several small ones with the fill tubes on them) then the easiest way to get it into the box is to use a length of small diameter hose and a suitable funnel running from the engine bay into the box. Fuel hose does the trick nicely.
Feed the hose down from the back of the engine bay towards the box, go underneath and pop the end into the filler hole just enough so the oil will go in and cable tie it up so it won't fall out and keeping it off of the exhaust - as the guide says, you'll need to have the engine running for the final top-up. Attach your funnel to the end in the engine bay, again, I use a couple of cable ties to support the combined weight of the hose and the funnel full of oil. Ideally you don't want the hose to be lower than the filler hole anywhere along it's length. Now smile smugly as you fill it without it half of it running down your arm!