While I truly hate the spoon feed system with enemy tagging and wall hack, I have, with the help of the splendid people on these forums, found a way to make the game slightly more interesting and difficult.

Never use the binoculars unless you have to as part of the story (for taking pictures).

Travel by foot or hanggliders. And flysuit.

Kill animals with knife or bow.

Whenever possible - use stealth to take out enemies.

The "I have spotted you" graphics is disabled, which means that I have to pay attention when I move around. Especially when I try to infiltrate.
I have no way of knowing if the enemy is getting a glimpse of me.

The tagging of enemies through the rifles scopes is disabled.

I have used a hack described elsewhere on the forum to disable the blinking of collectibles and corpses. I now have to search for them and I can't see them from afar.
Now the night is as a night should be - without the phospherous plants and boxes ruining the experience.

I accept the red blood drops on the minimap as me being able to hear the enemies stumbling like demented child kings all over the place.

I have restarted playing the game with the intention of disabling the towers first, collecting treasure and relics as I find them on the way via the minimap.

When I encounter enemies I take them out.

Then start buying maps to locate the other treasures and relics on the main map. Still leaving the camps alone.

When I get the chance to leave the north island I will start taking the camps out on NI and do the miniquests as well.

Once the North Island is empty of enemy camps and relics I'll leave for South island.

That should keep me occupied for a while.