Thanks Demm for you quick answer.
I tried with GPT installation but didn't work, I coudn't make the boot process recognize the SDD as bootable partition. I followed the instructions provided here but I was able to make the installer work when I created the partitions through the command-line. The problem was that kpartitionmanager create the first "unformatted" partition as FAT32 with label "ESP", no way to disable that and the installer requires a unformatted first partition.
I worked out to install KaOS in my SDD disk by formatting it as MBR, one EXT4 partition and disable Secureboot from bios. Installation ran ok and I was able now to choose the SSD as first disk to boot in the BIOS boot order. :-)
Thanks!