[syslinux] src/dst TIDs static @ 69 ?

[Jim Freeman]

At times our tftp servers are quite busy.
Our network folk are rebuilding, and are anxious to tighten security.

They hope to only allow tftp traffic on port 69, coming and going.
This would bypass the RFC1350 client TID=ephemeral and server ACK
TID=!69.

Is there any chance tftpd-hpa would do this with "-R 69:69", or would
this require tftpd-hpa to threaded, with a hairier connection lookup?
Can the syslinux client be constrained to send tftp from port 69?

[ googling, R'ing TFM, and even glancing briefly at the code don't
 provide quick clarity ...]