DS is 16mos and we have nap issues as well (though our whole schedule is shifted a bit since he sleeps at night from 11pm-10am) -- it's hard when social activities interfere with the nap but we just go ahead and do something 1-2 times a week anyway.
So our schedule looks something like this:
10am wake up, breakfast, shower, etc.
11-1 outing (meetup/playdate, story hour, playground, or library, depends on the weather/things going on)
1-2 come home, lunch, DS plays a bit if he's not ready to nap yet
4-5:30 play outside or in his playroom, or go somewhere if he woke earlier than 4
5:30 DH comes home
It sounds like your DD only naps from 11-12 most days? Around here, that would work so well, because everything is either 9/10-noon or early afternoon -- seems like everyone goes home for lunch around 11/12am but maybe that's just my area? But I bet if you get out there and do things with others, your DD will have fun and will adjust to taking a slightly later nap if necessary.
Maybe make a rotating schedule, like Mondays stay home most of the day, Tuesdays do a play date, Wednesday go to the zoo, Thursday do a meetup, Fridays do storyhour... something like that so the basic routine you have wouldn't need to drastically change day to day but there's more variety in the week.