If you stake them and keep an eye on it, perhaps. I wouldn't even try it where I am - here a 4x4 allotment is too small for 4 alone in a bed...

I will not disagree with Ray because he is absolutely right.

I will add that if you have the bed oriented to get the right sun pattern (so they don't shade other plants) you could fit a couple vining plants in, as long as you trellis so the trellis doesn't shade either.

Or if you are so inclined you could try 2 between the 1&2ft mark and 2 between the 4&5ft mark. But they will grow beyond the bed on each end and be very compact (crowded) throughout the bed. But that would give you so much squash/zucchini your friends/neighbors will stay away from you ;-)

Both are very vigorous plants with HUGE leaves, so the trick is to organize so they get enuff sun or they will stunt (shade) whatever they are near. Oh, the seedlings have to all be the same size when starting out except the vines should get a short head start (on the North side).

Confused yet? Did that make sense? Let us know how you made out.

Good Luck,
Gumby_CT