way i see it, several positions of fire will give the illusion of more people defending the area, therefore if you knock through the attics making 1 big attic, you can have people firing all along the row of houses, making it look like there are more occupants, throw in some mannequins nicked from a shop in some windows of the houses which you firing from (obviously not near the attic but in the other windows and not too many) will give any possible attackers other targets to fire upon, hopefully causing some confusion too
as for vehicular attacks, take a leaf out of the partizans book, use blockades, when someone gets out to remove the blockade, shoot em with a crossbow, this worked in world war 2 against tanks, im sure it'll work against less armored vehicles
also setup your own distillery, its piss easy and gives you a great source of fuel to use for those molotovs, saves wasting precious petrol...and you can use it for recreation and medicine too ^^
motion sensors would be awesome too, strategically placed in a perimeter around the property, alerting you to any intruders coming from different directions, what would also be good would be too tailor them so any signal sent by a motion sensors tells you which sensor it is, and therefore where it was set off
for any serious defensive scenario though i think you'd need more people, 2 that are capable of fighting is too little to defend such a broad area, but i guess it depends on what sort of attack
and how organised etc
oh and a good place to get glass bottles....recycling places, like the bottle banks at tesco's it occurred to me the other day when i went there to recycle some bottles, when the SHTF who the fuck is gonna pick up the bottles to recycle? no one, so there should be alot of glassware there ready for the taking ^^
another random though...thermite
(i bloody love the stuff) make some thermite packets ready to use (when i say that i mean rig them up with a rip cord or some such that you can easily set them off with, but not accidentally)...then have them in a box ready to use, you could use them for things like demolishing access to parts of the house, breaching locks and heavy duty doors, or if your feeling really really mean rig it above a doorway, nothing like a stream of molten metal on a raiders head ^^