With the basic $1000, you can maintain upto 200 of your 5/3/2 maintenance ships. Thats pretty good!
Even with 100 ships, you're still building at half the rate you started at.
The main sticking point for nomads is now building those ships. Making trade alliances is great for a constant supply of income, and will keep you out of military trouble at the same time.
If you are trading with 5 races, you are getting half as many resources as the average normal player! That is amazing for a nomadic race that pays peanuts for maintenance
In order to quickly boost your fleet size, you can indulge in a little piracy.
Capture a few ships, or a resource producing colony, and you will suddenly have vast new wealth.
Also, try fighters. You do get two extra sizes of fighter, and can mount sensors and solar panels.
For sure, you will need to micromanage and play tactical combats. For the most part, you should avoid combat.
I think the key is to focus your attention. Don't try to be a general commanding a huge army; instead play as a captain, leading your ragtag band of explorers.
You won't make much of a mark on the relative power graphs, but that is not what is important to a nomad.