You're thinking too small. You should aim for needing to found an Adminstratum world to count all your money.
If SP is not your issue, see if your GM will let you take a Conquest Star Galleon. It's my favourite choice for starting ship, doing a nice job of giving you a lot of power through Cruiser shields and weaponry, with the financial and hull integrity ability of a Transport. You can be quite powerful, but if you're not careful you can still get shredded in combat because they have abysmal armour.
If you want to keep something in the reasonable size though, the Orion Star Clipper has the amazing only keel mounted weaponry in the Imperial ships. This means you can both run away and attack people in ship combat. It's a win-win!