I think it would be fine. Just keep in mind, the nail spacing for sheathing is a lot more rigorous then most people think. It is rigorous, or in other words, nailed something like every 8 to 12 inches because that is what gives your framed structure rigidity. You should check your local building codes however. I might go ahead and plunk some more nails in it, or at least make sure it is nailed very well, then go ahead and toss up your siding.
It is interesting to note that my Uncle built one of his many houses using log siding. He did not both using any sheathing behind that home, instead using the rather thick siding as sheathing and siding both. Myself I would not do that. In your case though, I think that would be fine.
I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"