Personally I would dump TI Basic for the simple reason instead to increase the extra 16K GROM to be 24K of OS in GPL and 8K ROM.
i.e. GROM 0 (current OS), GROM 1 (currently TI BASIC), and GROM 2 (currently TI BASIC) also of course ROM 0 (Assembly OS)
RXB can run 99% of TI Basic programs especially if you put my REA TI Basic support routines there at that GROM space (4K used),
the computer does not know the difference between a CALL LINK called by TI Basic or XB, how they are handled in Assembly are the
same. And with 12K of added OS GROM a better memory manager could be created to take advantage of the SAMS memory. Not to
mention a F18 MK2 VDP memory manager also.
So your board would be able to be the most advanced TI on a single board.