After the End: Scouting the Scavenge Sites

I'm preparing for the second session of my Nu World After the End game, which is going to focus on the PCs scavenging in the ruins of Boston. As part of my preparation, I drew a map of the area they'll be exploring:

Sunken Ruins in Boston

I may have over prepared a bit: that map is about 250 by 160 hexes and contains around 70 or 80 potential scavenging locations. I'd rather be overprepared than underprepared, so I'm not regretting the work, but it did raise a concern that isn't, as far as I know, address in the ATE2 scavenging rules.

The ATE2 rules seem to assume that scavengers know where they want to scavenge. There are respectable rules for determining how many scavengers get hurt, based on the structural integrity of the building, and there are decent rules for determining what the scavengers find, based on what type of building they're scavenging and how many groups have scavenged that site before. That all works fine, I suspect, and I'll find out for sure tomorrow. But there aren't any rules for scavengers to scout or survey a bunch of potential sites, to determine which sites are the least dangerous and which sites have the best or most desirable loot.

I'm going to use the following house rules to address those issues:

• Danger Survey: takes an hour per six areas (ATE2 p 35). GM secretly rolls against the surveyor's Architecture, with a +2 bonus for every 3 points of positive or negative structural integrity modifier (SIM) of the area: it's easy to spot a solidly built or nearly destroyed building. On success, the GM reveals each area's approximate SIM, or exact SIM on a critical success. Failure means no information and on critical failure the GM lies. 
• Scrounging Survey: takes an hour per six areas. GM secretly rolls against the surveyor's Scrounging and provides each area's scavenging type (as per the table on ATE2 p 37, including both location type and looting level) on success; critical success gives a +1 on subsequent tests to scavenge any of those areas. On failure, the surveyor learns nothing and on a critical failure, the GM lies about the areas and there is a -1 on subsequent tests to scavenge any of those areas.

I already proposed these on the SJ Games forums, but the thread was ignored in favor of arguments about how realistic the current GURPS rules for crossbows and muskets are.