++1 on trekking bars on the mountain bike, the brakes and shifters swap on easily.
and you can get the function of lowering your upper body into headwinds
by reaching the front curves , further away, rather than reaching down.
into drop bars where you do need to change shifters and brake levers..
same result ...

Two types 26" wheel make good touring, most common wheel these days
for finding a tire spare of some sort, in some out of the way places,
I've Heard , you can find some sort of Mountain Bike Tire.

The other Big Wheel Trend is in 700C 35/37 ish tire., less common for spares
to be found if you need a tire outside of a major city.. or even in some ..

Having had a couple700c touring style build ups , then finding spares spotty,
I brought an extra tire on tours.. it didn't even need to fold.

and then found a 26" wheel trekking bike, World tour Worthy: Koga, from NL.

My most recent bike is a Bike Friday, a 406 wheel , 20"wheel being
2nd most common type wheel/tire in world distribution, to find a tire

and Bike Friday designs their bikes aroung getting you there at lowerst cost,
particularly when flying to or from the trip, end, front or back
where a regular bike in a box , gets a healthy surcharge, by the air carrier.

Because they knock down to go in a Suitcase.

They created a versatile design, or several, which you can get a lot of different
component setups.

I got a Pocket Llama, it has a set of disc brakes, a folding steering mast.
IG hub gripshift on Trekking bars ... whose figure 8 bend offers a drop bar variety
of hand holds,[ sides, near and far], rather than up and down, like drops.
and will take all the control levers off mountain bikes, directly,

whereas Mountain to drop bar conversions take a lot more work and different parts.

so consider your future touring ambitions, as to what you invest in for your touring bike purchase

Or conversion.. effort.

a Light frameset may not make the best touring bike, but having only one,
should not be an excuse to not go on a trip riding it,
if it is comfortable enough, to ride all day for a couple weeks ..