Peter- With a small parcel of land the key is the ability to use it all, I think your 400x1200 yds is the best you could hope for. Chipping Sodbury (Hawtree c1971) is 103 acres and about those dimensions. The course is 6800 yrds, has a practice ground, and no real safety issues.
150 yards is a nice width to run 2 holes, on older courses you often find two holes within a 100 yard band but I dont think many architects would be keen on signing their names to that degree of narrowness with todays 'laws'. Par 3s occupy much less ofcourse, perhaps even 1 acre per hole, sometimes a trick with small parcels is to have 5 or even 6 short holes in the layout, that way you can free up quite a bit of and for 12 or 13 holes.