Try to harden the comp and/or losen (counterclockwise) the rebound -but it does not make a major difference here (but i does help).
The easiest way to make it stiffer/more progressive is to ad more forkoil -but the best way is to change spring or as you say shorten the spring and add spacers (only spacer will give it less sag but will not make it stiffer).
I have the Baghira Forest edition with the S45 fork, it does not do the job at offroadrallys (it is 15 years older than the KTM:s setups -and it shows)..
My 1999 ktm 250 EXC fork is A LOT better (it is on a different level)
For usual roadtravel -the "baggyfork" works perfekt althow