Dessert for 50 people served outside. Any suggestions

You could make biscuits for shortcake and split them - James Beard's recipe is great: http://food52.com/recipes/17661_james_beards_strawberry_shortcakes

Put them out with a big vat of whipped cream (I add a little vanilla) and bowls of macerated strawberries - I'd also offer other berries or sliced peaches or plums, whatever summer fruit looks good - and guests can assemble their own shortcakes, with whatever combo they want.

Perhaps, Texas sheet cake (chocolate), banana split cake, and assorted cookies, bars. The first two are rather large.

Fruit skewers in a clear plastic cup with dollops of Greek yogurt in the bottom

Vast quantities of the very nicest in season fruit, with jugs of cream, ice cream if it's practical, whipped cream and meringues to make their own Eton Mess if you've got strawberries or raspberries, and some cute biscuits?

We had a celebration meal for 80 last year, and served 30lbs cherries and 30lbs strawberries with cream, evap milk (for the old fashioned ones) and ice cream. It was hassle free for us, and enjoyed by everyone.

Watermelon wedges on ice, assorted cookies. No scooping, no utensils.

Several different kinds of home your own baked cookies and dishes of gelato.

You can set up an ice cream sundae bar, using homemade or purchased ice cream. Serve direct from containers kept in coolers, or scoop individual portions in advance and freeze on a cookie sheet. Arrange bowls with a variety of toppings (nuts, fruit, chocolate chips, sauces, etc.) and let everyone make their own sundaes.

Banana pudding. I made this recipe (though I did skip that whole step of straining the pudding, just not necessary), http://www.evilshenanigans.com/2010/01/southern-banana-pudding/

Was delicious and took about 10 minutes to assemble from start to finish. Then into the fridge overnight. Nothing like cold sweet dessert during a sweltering heatwave.