Should a living trust that is 50 plus pages long have more than just a signature at the end?

A living trust does not have to have initials on each page and nothing prohibits having initials on each page.  The requirements for a trust are different from state to state and should be set forth in the trust statutes.  However, most living trusts are designed, in part, to distribute assets after death.  When they are designed this way, it is best (or, as in Florida, required) to conform the document to the state's Will statute. 

In Florida, that means the document must be signed at the end by the Settlor(s) in the presence of two witnesses who also sign in the presence of the Settlor(s).  In addition, it is a good idea to include the "self proving" provisions.  In Florida, that means that the Settlor(s) sign a statement verifying the previous facts, the witnesses sign to verify the previous facts, and everyone's signature is notarized.

I assume you are concerned about someone making a change in the body of the trust and inserting it without anyone recognizing this.  The likelihood that someone could get away with that is very small, perhaps non-existant.  Your lawyer will have a copy of the signed document, probably a digital copy.  You will have copies of the document.  Your financial institutions will have a copy (although not necessarily the beneficiary provisions).  If you are concerned about this, I suggest you place a copy of the trust agreement in a safe deposit box and notify your Trustee or successor Trustee that a copy has been placed there.