wide parallel bus

It appears you may be trying to use the SERDES as a PIO Expander, this is not how it is prescribed to be used and you will have a fun time trying to emulate the internal serial link using your host controller.

If you are trying to expand the IO capability of your device to support a physically extant 64 bit parallel bus, you will likely need an external protocol controller with a higher level protocol to your host or application controller, PIO expander chips exist but it will be tough to find ones that will at 100MHZ continuous through put.

Another, less canonical solution is to use a Dual Port RAM (DPRAM).

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The Component you listed DS92LV3241 is intended to be used in a pair with the DS92LV3242

The intent is to take an existing hardware parallel interface, and stuff it into a reduced signal count serial link in between.

Using this design pattern you can easily make use of 2 pairs of 3242 and 3241 chips to create a serial link between two existing 64 bit bus end points.

This requires the pre-existence of a 64 signals on either end, and precludes the bidirectional channels. For the distances you cite (30mm) you can also just route these two nodes directly.