it really kind of depends on where you got the seed
most new seed, especially , Hawaiin, has mostly bi-sex (%66 or more) plants.
%33 male and %33 F.
and i beleive a bi-sex can polinate a Female, but im not positive
because the stamens are set kind of deep in the flower.
The older way of planting papaya was to put 3 plants in a hole,
and kill (cut at ground) the ones that produced male flowers.
but leaving 1 plant per hole max. and 1 to 2 males every 100 plants or so.
Now since the percent of bi-sex is much higher, you dont have to do that.
if you are going to have 2 of more plants the % chance of both being male is low
3 plants -all male - is very very low.
(out of the last 10 seeds, i think ive seen 1 male)
so it depends on how many plants you want, and how much room you have.
they can get pretty wide from leaf-tip to leaf-tip.
and i dont suggest a lot of intermingling of leaves.
so if you plant them 6 to 8ft apart, the leaves will intermingle a bit
if thats in direct sun with a lot of hours, its probably not a problem.
they want a lot of direct sun.
some people will "top" their plants, cutting the top inch or 2 off when its about 4 to 6ft tall.
this will make it brach, producing 2 (or more) trunks the leaves come from
this can also make the plants take up more room
it helps keep the plant shorter, and will also produce more fruit.
(when i do this, i thin the flowers/fruit about %30.)