In the latest beta version there is some support for BETA48, check out TRDOS.CFG file to see if you have it:

# Beta48 should be set to 1 to enable Beta 48 compatibility (BETA128 software should work as normal in most cases)
Beta48=1

may I suggest this feature:

Because TRDOS v5 and up (Betadisk 128) uses different Adresses
from BASIC (15360/15363 instead of 15616/15619) can we
have an external command for a "redirection" ?

So e.g. a external program called .48trd
loads files from a TRD-Diskimage-File and it this programs
call ROM-Adresses 15360/15363, this should be redirected to
15616/15619. So BASIC-programs written for Betadisk 48k
can run directly with TRDOS v5 ROM.

Cheers,

Luzie