It always bother me when I get far into game (having nice base, fully equiped with diamond gears, etc) is easier to survive than starting off game with nothing.
So here my idea, make a mod (forge support so it has configuration) that it has slider for the following:
1. No enemies for X days (similar to peaceful)
2. Easy enemies after Peaceful for X days
3. Normal enemies after Easy for X days
4. Max difficulty (easy, normal, hard, no slider)
Each slider with ranging 0 to 30 days.
For example if I set
1. No enemies for 2 days (similar to peaceful)
2. Easy enemies after Peaceful for 10 days
3. Normal enemies after Easy for 15 days
5. Max difficulty: Hard
With that, I would be able to go thru 2 nights without enemies spawning, then for 5 days, enemies spawning easy difficult mode. Then after 12th days, difficulty goes up again, normal enemies start to spawning. And then after 27th days, Hard enemies start to spawn.