One potential compromise is that you can keep anything over 800 land for the first 3 or 4 clusters, and then once you have that, you first clear all the ranks and then you use remaining turns for plundering, exploring, etc.
Keep a set log-in time every single day and attack all fleetless empires during that time period. If you are consistent, eventually all the potential candidates for folks missing a log-in will be exclusively yours. Be sure to attack them as soon as they exit DP since any delay will end up pushing up your log-in time.
Keep special note of those who you see as low on borders, and monitor the feds for low PR empires who are possibly going inactive. Usually they`ll be on VM, but sometimes not.
Once you get your first c2 with over 20k land, you can, if you want, explore for 1 or 2 more nice c1s, but after that you need to completely abandon exploration. Keep everything above 500 land that you get in battle and cluster when you are able to (if you have no such planets, clustering 5 useless planets and then plundering can be a great way to save turns).
If your 2nd c2 is at LEAST 15k land (more like 17 or 18k in most cases), you will be doing great.
After the 2nd c2, keep attacking for borders and more planets. Maintain a high standard (500+ land) for the early c1s, but don`t feel bad about lowering those standards esp when you get to that last c1 needed to forge a new c2. In fact, when working on your 4th and 5th c2s, lowering your standards to a 300 land per planet minimum standard isn`t a bad way to go.
If you continue on this trajectory, you will end up on something like this:
20-22k land c2
15-18k land c2 (35-40K total)
12.5 - 14k land c2 (47.5 - 54K total)
7.5 - 9k land (55 - 63k land)
5k land (60 - 68k land)
Trust me, anything over 50-55k land for a c3 is PHENOMENAL for any empire. Most empires settle for much less.
By following this guide, you will be making your own c3s, even if you never win a single (good)