Possible To --enable-wallet After Syncronization With Blockahin? I am running bitcoind from the command line (--without-gui) and my system apparently does not have the correct Berkley DB version (4.8+). Therefore, I chose to run the program without the wallet enabled (--disable-wallet) so that Berkley DB would not be required.
What I am now wondering however, is if I sync the entire blockchain (300GB+) and at some point want to --enable-wallet, will I be able to do so without any incompatibility issues?
Furthermore, how can I update to the correct version of Berkley DB (4.8+) so that I can --enable-wallet. I already ran the script $home/bitcoin/contrib/install_db4.sh which did not alleviate the error when running ./configure to test the system for compatibility. I still get the error that the current version is incompatible.
What I am now wondering however, is if I sync the entire blockchain (300GB+) and at some point want to --enable-wallet, will I be able to do so without any incompatibility issues?

Yes, there's no issue with this. You will need to rebuild with --enable-wallet (or use the release binaries which bundle BDB), but this will have no impact at all on the synchronization state. You can switch between having the wallet compiled in, and back with no concerns.

Furthermore, how can I update to the correct version of Berkley DB (4.8+) so that I can --enable-wallet. I already ran the script $home/bitcoin/contrib/install_db4.sh which did not alleviate the error when running ./configure to test the system for compatibility. I still get the error that the current version is incompatible.

Depending on your distribution, you almost certainly have a version which is too new (5+), and many distros don't bundle old versions of it anymore. Bitcoin Core uses a very old version for compatibility, as newer versions would produce a wallet that can no longer be opened in older versions. Eventually this will be removed as a dependency except for some importing tool, but for the moment we just have to deal with it, or use the static release binaries which are reproducably built.