After taking a good hard look into all of this... I've decided to move forward and make my own TPMS system.

I'm taking a slightly different route than what I pictured above and I'm going with this setup pictured below. The location of the Honda plaque is just big enough to be replaced with a 2-line 8-character display that is enough to display pressure and temps for both tires simultaneously... and this location is easier to glance at than the side panel. I've already found an LCD that matches the Honda OEM display and so it'll look pretty good, almost OEM. I still plan to wire a glaringly noticeable LED that will alert the rider of pressure warnings or rapid decompression events and have this mounted near the gauge cluster.

I've already prototyped some hardware for the pressure sensor using Freescale's FXTH87 TPMS chip; proto board is shown below. I'm currently getting the programming sorted and then will move onto developing the receiver/display module.