As I see Abyss space right now, reasonable balance (almost withtout additional programming) would be so:
- Tier 5 is current tier 3 with loot table adjusted correspondingly. With random spawnes you have really good chance to lose any ship with any implants / boosters cause of time / unpredictable NPC spawns
- Tier 4 is current tier 3 with 40 minutes cap instead of 20 minutes. At least time will not kill you. Random NPC spawn still do.
- Tier 3 is current tier 2. You should be really good to run this with 99 % chance of success. Cause timer is still 20 minutes cap and thats is not much.
- Tier 2 is current tier 2 but with 40 minutes cap instead of 20 minutes.
- Tier 1 is ok as it is now.
TL;DR - skip current tier 4 and 5 as totaly unpredictable, almost no oone will run them. Good job at tier 1-tier 3, just adjust time limits on some of them to break the tiers from 3 into 5.