[EE] High reliability store and recall of data in EEPROM

I have a need to store some data in non-volatile memory, with the caveat
that corrupt data MUST NOT occur.  Things go "big badda boom" otherwise.

Offhand, I came up with storing each byte as a four byte array (I have TONS
of space available)
If I'm storing 0x01 then it would look like this:

1       2        3       4
0x01, 0xFE, 0x01, 0x55

Xor 1 and 2, result must be zero.
Xor 3 and 2, result must be zero.
compare 1 and 3 result must be zero (not sure this is needed)
check 4, must be 0x55 otherwise a wild write has happened in EE.
Finally the values allowed will be sparse, and likely only a single bit
will be set, so I will check that the value I read is one of the allowable
values.

If any of those checks fails, we render safe and halt.

Is there a more "rock solid" method?    What would be done in an automotive
environment for something like throttle position?   What would be best
practice for medical life safety?