I have done as you suggested and I see it definitely simplifies the projection.
The big problem with entering a false DoB is that it makes the lump sum commutation number completely wrong.
Would it be fair to assume that if you take maximum commutation that you can just multiply the difference between the full immediate pension and the post-commutation amount by the number of years until age 55?
If I am correct then my lump sum with maximum commutation becomes significantly larger if I were to PVR in the next few years.
BV