[Elecraft] K3 Transmit Xtal Filter Question

[Geoffrey Mackenzie-Kennedy]

Is there any reason why the K3's 2.7 kHz xtal filter normally used during 
transmit cannot be replaced by a narrower one, say 2.1 kHz, with the 
required adjustment of the carrier frequency?

I am looking for a lightweight rig to take on holiday style "DXpeditions", 
and the K3 would meet the requirement if its SSB Tx bandwidth can be reduced 
by a narrower filter.

My apology if this has been discussed before.

73,

Geoff
GM4ESD