Three vessels, all optimized for maximum speed & compact size.
One solar-powered variant, exclusively for inner-planetary logistics.
A second, nuclear-powered variant for your first Aquilo deliveries.
And a third, fusion-powered. for when you've conquered Aquilo.
They weigh 281, 306 & 285 Tons respectively. And share the same Top-Speed of 482km/s with legendary thrusters.
All of them feature a simple 3-combinator PID-controller for fuel usage. Optimized for higher thrust when available, and higher efficiency as fuel empties. With "smart" inserters for throwing excess material overboard and controlling crushers and assemblers.
The solar variant can get away with everything being normal quality. Just set a platform hub circuit condition to not leave orbit until A=100 and until ammo is more than 300. The first thing you'll want to upgrade to higher qualities is the solar panels.
The Nuclear version runs on a small power deficit during peak power draw. Though it's not an issue, if possible ship up the highest quality reactor, heat exchangers & turbines you can afford. Set a platform circuit condition to not leave inner-planetary orbit until ammo & rockets are greater than ~300. The nuclear reactor does need to be kick-started with some solar panels. (for water)
The Fusion variant doesn't "self-prime" with fluoroketone coolant. you'll have to manually "pick up" some barrels (with Q) and "place" them into an assembling machine set to "empty fluoroketone barrel (cold)" on the left side of the reactor. with some solar-panels to give it a kick-start.