Remembering Stuart's idea of reclassifying terrain - introducing scrub etc., in order to have an ability to advance slowing with infantry without being shot to pieces, I think that infantry crawling in the open are assumed to be using all the ridges, bushes hollows etc. to conceal their movement. However, they will not always be successful hence the need for chance testing.

I propose that, in order to keep it simple and within the spirit of the game and not needing to differentiate between types of open terrain, infantry crawling in the open are considered to be in soft cover (arty makes no difference) but enemy have a chance to spot at 24" (5-6), and auto spot at 12". Thus anyone using this tactic will need to consider two turns normal 6" movement required under fire before reaching their target!

I think that this will simulate the slow, deliberate advance using all the cover available, until there is nothing left but to charge the objective and keep one's fingers crossed! The fact that they figures will already be placed on table for the enemy player to see will simulate the troops "feelings" that someone is out there but there is insufficient "target area" to justify firing at them. i.e. players will still be aware of an enemy approach in the open, albeit they might have to bide their time before opening fire.