I thought that I could use the pitch, roll, and yaw angles of the body frame

Whether this is true or not depends on the relationship between the Sensor and Body frames. You need to determine Tb2s (the full pose of the Sensor frame relative to the Body frame.) Then the calculation to transform a Ps (position in Sensor frame) to a Pb (position in the Body frame) is:

Pb = inverse(Tb2s) * Ps

In the case where the Sensor is attached to the Body, it is not necessary to know what the roll-pitch-yaw of the Body frame is. However, if the Sensor is not attached to the Body (maybe it's mounted on a wall), then you'll need to first calculate Tb2s through a frame common to both e.g. Body -> Map -> Sensor.

I thought that I could use the pitch, roll, and yaw angles of the body frame

Whether this is true or not depends on the relationship between the Sensor and Body frames. You need to determine Tb2s (the full pose of the Sensor frame relative to the Body frame.) Then the calculation to transform a Ps (position in Sensor frame) to a Pb (position in the Body frame) is:

Pb = Tb2s * Ps

In the case where the Sensor is attached to the Body, it is not necessary to know what the roll-pitch-yaw of the Body frame is. However, if the Sensor is not attached to the Body (maybe it's mounted on a wall), then you'll need to first calculate Tb2s through a frame common to both e.g. Body -> Map -> Sensor.