While doing research i came across similar issue, after performing all the advised activities in other forums finally i decided to update 5.5 U1 to the build number 1746018 and then attempted to create software iscsi adapter. After hours of observation hostd didn't crash and it was stable.
Also, i dont believe this is hardware compatibility issue as the host i worked on is HP BL460c G6 which is not compatible however the update fixed the issue.
Please hit like if this has resolved issue in your environment.
Martin Meuwese, your excellent description of your problem helps me to solve my problem!
Thanks! an Congratulations!