My father had a duckunder on his layout. The floor was linoleum and the benchwork was so strong that I could take a run, slide down on my knees and pull myself under using the main beam on the layout as a grab handle. Of course that was 15 years and a back surgery ago so I wouldn't be able to do that any more. Anyway I would still go with the duckunder even though I'm 6'9" tall. I'd just take my time crawling under and pad the benchwork. Laying a bit of lino on the floor if you have carpet might help too.