Python3 bytearray padding

Hi,
I'm trying to create a padded bytearray in Python3.
Currently I have something like this:

inputstuff = [
('A' , b'ABCD'),
('B' , b'EFGH'),
('C' , b'IJKL'),
('D' , b'MNOP')
]
BA = bytearray()

for thing in inputstuff:
        BA.extend(thing[1])
 
print(BA.decode('latin1'))
print(BA)
 
for thing in BA:
        print(thing)

This works and gives output like this:

ABCDEFGHIJKLMNOP
bytearray(b'ABCDEFGHIJKLMNOP')
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80

Which is expected.

However, what i'd actually like to do is pad the bytes I add to the bytearray with blanks such that it would be more like this:

ABCD EFGH IJKL MNOP

Obviously I could just add spaces to the end of each string defined as A, B, C and D - but i'd rather not do that as it would get complicated when I use this code in a real scenario where these are objects being passed into the function etc.

If anybody knows how to do this i'd be very grateful of your help.

Regards,

Phil