Security of password hash with known prefix and appendix
Except against rainbow tables, it makes no difference whether you've prepended or appended any bytes if they're known and static. Both may as well not exist.

So the scenario is reduced to "doing a checksum of" (presumably trying to hash) a 32-byte password. 

There isn't a CRC-128 in common use, but if you extended the CRC algorithm to 128 bits, you'd get a completely insecure transformation. CRC was designed for simplicity and low collision probability, making it reversible. There's a paper specifically on reversing CRC - https://sar.informatik.hu-berlin.de/research/publications/SAR-PR-2006-05/SAR-PR-2006-05_.pdf - and the process can be implemented by a decent high school student.

Algorithms resistant to that - producing a true one-way transformation - are called hashing algorithms, not checksums. Popular examples of hashing algorithms include SHA-3 and SHA-2.

For passwords specifically, an even higher level of security is often called for, such as using key derivation functions (PBKDF) - bcrypt, scrypt, argon2. In addition to the quasi-randomness property that hashes have and CRC don't, PBKDF deliberately tie up additional computer resources to somewhat improve their brute-force resistance.