Should replace one of the equipment crates with a "broken" equipment supply crate.
They're useful for storing empty, or as storage for currently unused resource barrels.

You know the broken crates, the ones with the lid missing so they're a container that perfectly fits barrels stacked inside it?

I'll see what I can do -- no promises though - those crates have so many variants...

It's just the suit\tool storage ones, they are wide enough to fit barrels inside and stacked ontop one another.

I added a Cargo Container 3 Under4 Static Objects - not sure if that's the one you wanted but it does fit multiple barrels and I tested it with 3 so I know more than that can fit if you really take your time - plus an added benefit of Static Objects: They Won't fly to pieces if you shove them too hard :D

Oh that one. Actually meant the larger suit\equipment storage one on the right as you exit the airlock.
With that type, you can lay barrels down inside it fitting (usually) more than 10 inside it. It's the perfect width from the front to the back to lay them down inside it side by side, Its possible to lay 4 or 5 barrels per-layer and, with the larger type one like that one, you can stack them 3rows high without without them flying out in the tray of the cargo truck.

Ofcourse, If its just a storage for outside your habitat. then you'd easily be able to fit close or over 15 in the pile since the box wont be moved ect.
And yeah, those are solid and don't have breakable parts.

That smaller general purpose one you added isn't the best for barrel storage, Seen it used once in a pre-placed pod with stuff it in. Except the barrels got stuck inside it and I basically had to lift then turn it upside down and bash it around on walls or any objects I could find around to "try" to unjam them.
(they Get stuck when stacked standing upright is what I'am saying) But that the equipement one is slightly wider than 4 or 5 barrels so it leaves tinny little spaces between them, so the barrels can freely move around, or in this case, belifted\fall out.

Try it out. Its pretty efficent for storage, Lay the barrels down so the top and bottom of them just fit into the narrower section, with the other barrels laying next to it along the length of the container.
Then you just keep roughly orientating more and lay them ontop the bottom layer then the next layer, you can fit a surprising amount inside it. With the best part being, they wont escape and they take up much less space than just having them stewn across the floor for you fall over on them (lol!) should add 2 or 3 of those laying around, Later they only get more and more useful ;)

Sorry I'll look again another day - for now can you deal with the one i have - I have a life outside scenerio creating y'know.

In consolation I do know which one your talking about but it's kinda a matter of finding it in the editor, it has a strange filename so i haven't been able to find it yet.

Yeah, heh.

If you are curious, in the manned single player campaign they give you one with barrels inside. Got the idea from that, I was surprised when I could stack so many inside and on the pile.
Also, when the barrels are empty the entire container can still be lifted and carried else where.

Here. Check out my screen shots in my profile if you want a clear idea of what I mean. I stacked them like that, 4 per-row, 3 rows high, 12 barrels into that tinny space they cannot escape but can still be easily lifted out without them getting stuck. technically, you could also stack ontop of those if you do not plan to move the container. Which means 16 barrels in total stacked neatly and easily, you just roughly align the barrels and drop them in, then physics will do the rest for you.

The last screen shot from TKOM there, All those barrels fit into that thing.
I use this method to move empty ones or to mass store\move with the cargo truck, 12 barrels in one container, thats 1560 worth of whatever material\s is in those barrels.