The V-2 carried a 1 metric ton (2200 pounds) payload for a range of about 200 miles. It reached a peak altitude of approximately 60 miles. Military ballistic missiles are typically classified in terms of range. Intercontinental Ballistic Missiles (ICBMs) typically have ranges on the order of 5,000 miles or more because continents are pretty far apart. Intermediate Ballistic Missiles (IRBMs) like the old Thor or the 1980s Pershing II typically had ranges on the order of 1,500 miles. The V-2's capabilities are about the same as a Scud, which is considered a short range ballistic missile.

Comparing that to the SpaceShipOne (SS1), I don't see a lot of room for concern. SS1 was designed for the X-Prize's requirement of lifting 3 people 100 KM high. The FAA standard weight per person is 170 pounds, so SS1's payload is probably closer to 510 pounds (~232 KG) than to 500 KG.

While both the V-2 and SpaceShipOne reach about the same altitude, I doubt SS1 has a great deal of downrange potential. It was designed to fly essentially straight up, hitting a speed over Mach 3 (WOW!!) in the process. If you reduced the ascent angle to a more ballistic trajectory, you'd probably end up with a higher velocity, one that I suspect would be faster than SS1 was built to handle. Every aerospace vehicle is designed to a specified performance envelop of altitude, speed, g loads. Stay inside the envelop and you'll be fine. Go outside the envelop and you're asking to die. Trying for a ballistic trajectory in SS1 would, I suspect, put you way outside the speed verses altitude envelop.

Now, the hybrid engine on SS1 by itself could power a missile designed for a ballistic trajectory. If it were air-launched like SS1, you could probably be able to send a warhead of 500 pounds (1/4th of the V-2's load) for perhaps 200-300 miles. Hardly qualifies as a long range missile, IMO.