Is there any shot at routing UF outside the structure and then coming in from below?
It's not too uncommon for log cabins to have the bottom log resting on drained soil/ sand/ somesuch.
In which case, what you really have is a digging project.
Auger bits -- with extensions -- and a 7/16 impact auger driver -- can take the UF straight down into the soil.
BTW, most log cabin construction uses a pretty crude mating between the horizontals. This is corrected by daubing the gaps with local material: mud/ moss/ bark/ whatnot to create a wind seal and some sort of crude insulation. This corridor can be opened up if you're close enough to an open end -- by drilling horizontally all the way through. You'll want extensions. Then, cork up your run with a suitable dowel and marine glue when all is done.
There is a bit driver that you can purchase -- advertized in the back of EC magazine that permits bits as long as your all thread. (3/8 x 16 -- to ten feet -- unless you add a rod coupling and some thread-locker.)
Because the gap is already pretty much there, you may find drilling in this slot shockingly fast.
Rotary grinding heads are available for small angle grinders such as Metabo and Milwaukee and Makita and... They'd make fast work of roughing in any receptacles to the horizontals. Then you could follow up with Norton's sanding flap-discs -- with a very aggressive grit -- then step down to a finer grit, etc, etc.
I would recommend using double-gang receptacle penetrations as they're going to be easier to work -- and solve modern needs.
Don' forget to consider the need for LV, CAT 5, 5e cables.
Lastly, don't forget that you might get away with drilling horizontally straight under the building -- even if you have to farm out some of that work.
There are a number of under-the-sidewalk boring rigs that could well get you underneath the building. Then, you could 'chase the bit head' (metallic) with magnets, sound, or what not, and cut-in floor boxes. They may be far sweeter for the owner than Plan A.
You could put floor boxes as purely pulling points underneath cabinet locations.
Leaving the interior undisturbed has endless advantages.
No-one is going to complain about ditches dug outside.
Floor boxes can be encased in mud/ concrete, too. They can also be insulated with low-expansion foam. (The 'crack' stuff is too powerful and will distort any plastic box.)
Any ditch digging can be held to a mere 14" by using GFCI protection -- back at the panel -- of which I don't know whether it's inside or outside.
It's either the above -- or call in trained termites -- and keep them on piecework.
