Another question about Yiddish pronunciation

I would like to pronounce (using Weinreich's protovowel designations):
A1 = /a/
A2 = /o/
A3= /o/
E1 = /ɛ/
E2, E3 = /aj/
E4 = /aj/
E5 = /ɛ/
I1 = /i/
I2, I3 = /i/
I4 = /a/
O1 = /o/
O2, O3 = /oj/
O4 = /oj/
U1 = /u/
U2, U3 = /u/
U4 = /oj/

but I couldn't help but notice that this is one fewer vowel phoneme than any individual dialect of Yiddish. On the other hand, I'm not using sabesdiker-losn so together with the consonants it's still more phonemes than Northeastern Yiddish that does use sabesdiker-losn. Am I being too reductive? If so, what should I do if I still want to pronounce all of the vowel diaphonemes that appear in Hebrew-derived words as described?