Stay with tubes. 

For touring, I drop my gear range down to 36 chainring and 16T sprocket.  That is very similar to your 43 and 19 ratio.  If it is too steep for that gearing, it also is too steep for me to pedal while keeping my heart rate in a reasonable range.  Thus, I get off the bike and walk it up the steeper hills.

Have you ridden much on rough trails before? 

I'm heading over to Canada (from Scotland) this summer, to ride south for around 1000miles to Jackson, Wyoming on the Great Divide route with my son.

The GDMBR tends to get talked about today as more daunting terrain than it is. Once the bikepacking scene took off, it embraced this route which meets the Bikepacking.com definition because it is majority unpaved. However, before that, the GDMBR was commonly regarded as a touring route and people rode it on conventional touring bikes like the Surly LHT, with 2.00" or 2.15" tires. Loads of blogs were written about this, some of them are still up today. So, if you can fit 54 mm, you’re already well prepared, even if you might want to take advantage of being able to fit something slightly wider in front.

On the same page he also explains why you're likely to get 20,000km + from an uncovered KMC X1 chain with minimal maintenance.

I think that depends on where and when you ride. I live near the coast and ride in all weathers, so when it rains the tyres pick up wet sand and mud and a rim brake sprays it over the chain, even when I don't go off-road and keep to tarmac.

The best I have managed so far is 8,300 kms with an old type bushed 1/8" chain used on a hub gear bike. This was long before I knew about the ChainGlider. More typically, I would get between 2,000 and 4,000 kms on a derailleur bike. Bromptons are worse, typically 2,000 kms or less, probably because the transmission is closer to the ground and picks up more muck.

KMC advertises 3,500 kms plus for the successor to the X1 and 10,000 kms plus for their long-life 1/8" chain if used with their own 1/8" chainring and sprocket.

The photo attached shows the results of one of my first rides with a ChainGlider The wet sand on the outside of the ChainGlider would have gone on the chain if it wasn't covered.

In my experience, a ChainGlider keeps most of the mud and sand off the transmission. Water gets inside when it rains, but it drains out. A ChainGlider works for me to significantly reduce transmission maintenance.

For all the recommendations that the Chainglider gets here from a member or two, Thorn/SJS did try to dissuade me from buying one from their own shop a few years ago, calling it a “poor piece of gear” that had disappointed them in their own testing of it.

It’s also worth pointing out that some of the most popular long-haul bicycle-travel routes today involve water crossings. A chain is going to get dunked several times in just one single day on the Baja Divide, for example. A Chainglider is downright counterproductive then, it would trap water inside.

I have now put over 20,000 km on my belt drive and I am very satisfied. I think it is worth it in time savings alone, as it does not have to be cleaned or lubricated. No more expensive trousers being stained with oil, too. I have never even had the noise that some report, except for when I rode one wadi in Oman where the dust must have been of a peculiar composition, and then merely pouring some water over the belt was enough to make it quiet again.

My opinion is that anyone who's still running a bare chain on a hub gearbox might as well go back to the days of constant running replacement expense and maintenance work and filthy derailleur.

My own opinion, based on my (at first sceptical) test of a ChainGlider is that :

- A hub gear system with ChainGlider keeps the transmission much cleaner and requires significantly less maintenance than a hub gear system with a bare chain.

- A hub gear system with a bare chain requires significantly less maintenance than a derailleur system. And when it does need maintenance, it is much easier to clean 1 chainring and 1 sprocket than multiple chainrings/sprockets and the rear derailleur (front doesn't need much cleaning).

On condition, of course, that the hub gear is reliable. I have had one or two unreliable hub gears, notably the first version of the Sturmey-Archer Sprinter 5-speed, which was a real pain.