What an amazing project AC, very inspiring!
Since taking on an extra plot at the allotment, I've been thinking about how to manage the workload without injuring myself or burning out.
Like you've mentioned already, direct seeding in the way to go. I'd also suggest going a step further and making scatter mixes of salad leaves, chard, herbs, flowers etc. Scatter on the bed before a good rainfall is forecast, rake it in if you feel like it (I usually don't...) and a few weeks later, come back to harvest.
Bonus points for keeping the weeds at bay, can be used between bigger crops like tomatoes, squash, climbing beans, corn etc.
Another area that I used to find back breaking was composting. Now, I compost everything in place (chop and drop) or compost in the pathways (but that's a trip hazard for a community garden). The only thing I remove is diseased material that could spread but there's very little of that.
I'm sure they are many more ways to cut un-necessary labour or concentrate the labour into community days like "potato harvest day" (promise of cake and coffee would help)... You've got this!
