we tried all AD and AD/AP, but got hosed by shooty girl and katarina's ult. the first time we tried it, we didn't have the masteries and didn't all have ranged, and we got annihilated. kat went 42-3-15 in about 25m. the second time, we didn't have masteries but had all ranged, and still got merc'd - but they beat us in towers
so, don't know what i'd do differently. i'd prefer to have cait and kog in there over some other champs that we played, like malz. some combo of sivir, kat, kog, ashe, cait, tristana, and shooty girl could probably do a lot more than the teams we ran with today. alternatively, include a character with lane-sustaining heals and CC like alistar, or a buff character like janna, sona, or soraka. soraka and alistar both do decent damage early, and their healing abilities will counter what hit us the hardest - not being in lane half the time because we took two hits and were almost dead - and will prevent being dead ten times before level six.
i still like the 1-4-0 strategy i suggested. have one character with a ridiculous AOE ult like kat or fiddles solo a lane, grab ridiculous exp early between fortify and general farming, and then go blow people up after hitting l6 early. since there'd be someone in the lane, likely the other team wouldn't collapse five mid right away, so you'd get a lot of 4v3s at low levels, where you can carve up a hero right away easily and be done with it. it'd also prevent blowing fortify five times in the first ten minutes, since they'd only have one free tower to push. i don't know if that'd make pushing towers harder or not, but i think that it'd help balance the EXP loss that you get with five in a lane. plus a l6 fiddles with magic pen boots and a rod or two - totally doable in a solo lane with a bit of tower gold - would easily deal 60-75% of most enemies HP in one crowstorm, not to mention the crazy stuff having an ability like fear with four ranged AD heroes right there represents.