If you have a 200w solar panel , you 'should' use a 200 watt controller. 2 reasons.
1) 100 watt controller will never allow more than 100 watts, so 1/2 the solar panel power is never used.
2) unless the 100 watt controller is properly designed, the 200 watt solar panel could destroy the controller.
Nowadays you can get a 'package', panel and controller, might be cheaper. They're all basically 'Made in China',so unknown quality and doesn't matter who sells them...A or HF, the source is the same.
Since you're in the middle of the bush, buy the biggest panel(most watts). You have a maintenance issue, you're not there to remove snow, downed branches,etc. so you need as much power as possible whenever the sun comes out. Winter(at least here in Ontario' is very hard on solar systems. Mr. Sun sleeps in late in the mornings, goes to bed early, herds of lazy clouds saunter cross the sky... so usefule solar energy is very,very low. Toss a 1/2" fo flakes on the panel....poof....near ZERO power to be found.
KISS says buy 5 identical 100 watt systems(panel/controller/maintainer) Wire 4 up,run the 4 wires through one 3/4" hole, caulk to seal. Keep 5th system ,in a box, in the shed..as spare parts ,incase one of the 4 systems fail. There's 'safety in numbers'. If 1 of the 4 systems fails, NOT a big deal. If the ONE highpower system fails, all 4 batteries could die.
Yes, you can buy a 'one-system-does-all' product but it'll cost more than 5 of the smaller ones.