MPU-6050 soldering error angle compensation

Hello
I have to compensate error created during soldering (cross-axis error) - it is not possible to mount sensor to pcb perfectly perpendicular to all axes.
I need to sort out this, because for a flying R/C models it is unprecise, each pcb I've made is not identical.
I propose to solve it with a transformation matrix which is filled with data from accelerometer/inclination. I need just something like calibration platform what is perfectly parallel to ground.

For example:
x1 = 0.8*x0 + 0.1*y0 + 0.1*z0
y1 = 0.1*x0 + 0.8*y0 + 0.1*z0
z1 = 0.1*x0 + 0.1*y0 + 0.8*z0

I need it only for Gyro output, is MPU accelerometer so precise to recognize so small inclination?

Do you think it is correct way or do you know a better one?

Thanks