If your original data is not a byte sequence then it would indeed work. Otherwise you have to convert it back to bytes yourself, but no small x exists such that 10^x is just barely smaller than 256^y and bignum would be necessary for efficient encoding. Base45 doesn't need bignum and only incurs ~3.2% overhead [1] compared to the pure octet mode (which might be unsuitable for decoder compatibility and other purposes though).

[1] 32 original bits = 4 original bytes = 6 base45-encoded letters = 33 bits in the alphanumeric mode, so the overhead is 1 - 33/32 = 0.03125 for 4n bytes of data.