Hi Tommy,
Normally when we have questions about pushing the voltage limits of the T200, people have 22V or 25V in mind. In this case, you are correct current is the real killer, not voltage, and as long as overall power is limited to about 600W it can be possible to run at higher voltages with a number of caveats. You can read more about this here.
However, 48V is so far beyond the design voltage of the T200, that I doubt it would run well at all even if aggressively current limited. With that said, we have not tested this, and I have no idea what would happen in practical terms. Overall, I cannot recommend doing so.
This point is somewhat moot however, as the T200 has 14 poles and runs at about 3800RPM at full throttle. Electrical RPM is thus 3800*7=22600, almost double the 13000 your controller can top out at in sensorless mode. Our thrusters are based on sensorless brushless motors and do not have any hall effect sensors.
-Adam