Many thanks to all who have responded to my request about how to observe Lower's Nebula.
A friend of mine, Holger Münz here in Germany, has supplied by pers. comm. the following observation with 8x42 binoculars:
"Instrument: 8x42 binoculars. Filters: H-Beta on the front on one side, UHC on the other, didn't have two H-Beta at the time.
Sky quality: Good rural sky in southern Germany, NELM approx. 6m5.
Dark adaptation: Extremely good, spent 1/2 hour in car listening to music with eyes closed, followed by 1 hour looking through the binoculars with the two filters.
Observation: Noticed towards the end of the observing session, while panning around between Monkey Head Nebula (which appeared very bright!) and Orion, quite by chance a nebula that I identified later at home as Lower's Nebula. Size similar to Monkey Head. Visible with direct vision and easy to find again after panning away and returning.
During the observing session I had previously tested one-eyed and binocular observation of the California Nebula with the filters and found that involving the second eye - even though "only" with UHC - made a major difference to visibility, notably in terms of whether the object was visible directly or only in averted vision."