Good for you Nicolas… TOC has a hard-to-counter set of arguments for battery power in your climate.
I think you could do track power also, TOC and I had a long conversation about your situation.
But it will be easier for you to go battery.
If I was living where TOC is, and I wanted to stay track power, and have remote control and sound I would:
Use stainless steel track, the stock joiners and spot weld stainless steel jumpers between track sections. This will keep continuity and allow track to move in the joiners and you don’t have to buy any rail clamps.
Using a lot of power feeds for a properly constructed layout is a myth, so I would feet TOC’s layout with 4 feeds max if it was mine and track power.
Reverse loops are dead simple in DCC, $50 each and they wire to the adjacent rails, no long feeds back to power required.
The cost per loco would of course be less since no batteries, no chargers, and the complete sound and motor decoder is under $200. You have to spend $300-$400 a loco for battery. (realize in my case I have a lot of locos)
I have family in that region, so I may install one just to PO TOC ha ha!
AMS aluminum is about $3.00 a foot for 5 foot flex, $9.50 a foot for SS, so a 500 foot layout would cost (track only no switches) $1,500 vs. 4,750, so $3,250 more, so throwing in a top of the line wireless DCC system, at around 16-20 locos, top of the line DCC on SS track vs. battery power will be cheaper.
I heard you are not doing a big layout (so track cost is NOT the biggest item), but the locos and control system are.
So for you, battery should be best, again given your hostile climate.
Greg