Yes, a FIKUS works OK. The ones marked for the Summar are marked at the fully collapsed setting, although I've had no trouble at the 50mm setting.
Of course, the correct rectangular SOOMP hood is more effective, but it's large, and expensive. You worry about losing it, which you don't with a FIKUS.
A screwmount camera, 35/3.5 Elmar, 50/2.0 Summar, 90/4 Elmar, Imarect, and FIKUS makes a great travel camera kit.