I did this with onions this year(3 inches apart) and saved alot of extra work(making trenches).I always plant staggered(first row starts at 0, second row at 6 inch, third back to 0), with 6 inches in all direction for garlic and its been plenty of room.I do keep my ridges minimal height ,as wind can be rough here.Your idea sounds good to me and adding a few inches in row width is worth the yield, your soil is well taken care of.

Thanks, baygrower. Your suggestion to keep the ridges at a minimal height sounds intresting. I have the impression I made mine a bit too sharp this year. Next year I certainly will apply the planting in a staggered pattern.

The staggered pattern i mentioned was a bit off.I start first row at beggining of measuring tape and plant second row at 3 inch or so and third row at beggining of tape.It just gives me alittle more room for roots on the diagnols,as the roots tend to fill up the trench.