With a reduced agitation scheme like this, I usually stick to at least half the dilution I use normally, and I only use it for carbon transfer printing where I want pretty extreme contrast anyway.
So in short, I'd just reduce developer concentration to maybe 1+1+250 or so and give it another try.
But frankly I'd recommend sticking to a normal development process with agitation every minute or 30 seconds and, shorter development time and a 1+1+100 dilution. With the process you're using now, you won't get very meaningful edge effects, nor will the compression of contrast be very helpful either (as you've noticed) - besides, this is a film that doesn't really need the latter anyway as it's an easy film to keep contrast in check with.
Just for testing I'd recommend doing a roll of film using e.g. development times from the massive development chart and normal agitation, see what you get, and then modify the process to improve any aspect(s) you feel should be changed.