(Paraphrased)
First attempt - played to 2515.
1. forum hint of scouts as researchers.
2. Lost my starbase a number of times
3. around 50 years (I think) I had approximate tech parity ... jihad cruisers and some BB's.
4. Then I made the mistake to attack neighbouring planets in full force and attempt to keep them. Managed to capture Blue Giant, Hill, and Spittle without difficulty, but was booted off all of them by enemy Jihad BB's against a divided defense fleet.
5. I am ready to give up, my HW was bombarded with a large packet and apparently packets go before defenses built, so the expeditions plus the package dropped my HW to around 500k with nothing to show for it and my fleet more or less gone.
6. I will try again and do more guerilla style warfare from my HW, conquering a planet and transporting all minerals back until I have an expedition fleet that can withstand an enemy attack.
7. It is quite annoying that it seems very hard to keep my mine field up and getting their minefields down. I had something like 20-30 frigates laying mines, and sent out sorties of 10 gattling frigate sweepers to jump in, sweep, jump back. Is there a better way to do mine field management?
8. I guess I also need to learn about using chaff against enemy jihad BB's... I also used beamer cruisers (move 2.5, 2 sappers + 5 phasers or 6 Mk IV blasters) but they just die so quickly because they run at the enemy, even if the enemies are still fighting among themselves, and they seem a bit expensive to treat as disposable.
9. Anyway, the challenge is quite fun and instructive, I hope that the second attempt goes better!

10. Edit: second attempt went much worse. The AI attacked with stacks of morphs much earlier, forcing me to rebuild my station quite often; and it feels like I was less lucky in the tech lottery. Turn 27 they sniped my starbase (13 cruisers and 10 destroyers still alive) and immediately bombed my population down to 57k. Game over...