Yes it is possible. Especially if the North side of the garden is the 12 foot side. You'll want to plant tallest to shortest North to south. Peas and Spaghetti squash on the trellis. Although you probably already missed the english pea season. You could do southern peas (blackeyed, crowder, field peas etc.) Tomatoes in 4 squares each, they go in the second row and spill into the third. Bells take 1 to 2 sq. feet and are the next tallest, and last are the Squash and Zuch's in 4 squares each in the far south. So the layout would look like that below assuming you have a trellis to the far left and either trellis or cage the tomatos.

ssq tom tom csq
ssq
pea tom Bel csq
pea
pea tom Bel csq
pea
pea tom Bel zuc
pea
pea tom Bel zuc
pea
pea tom Bel zuc
pea

I think 6 pea plants go in each pea square. Hopefully this makes sense to you.

Susan

Please accept the following statements as constructive - not criticism. That's not the intent at all.

I'm assuming this is a raised bed......
Personally, I wouldn't put the spaghetti squash in there. I have 48 running feet of trellises in my garden, and i've trellised anything you can think of. If left to grow as it wants, it will engulf everything on that end of the bed. Of course you can keep it pruned back, but the yield you'll get won't be worth the time or space. I tried to introduce spaghetti squash in my raised bed one year, and boy that was a mistake! Now, I do my pumpkins and winter squash in their own bed/trellis.....

Summer squash can certainly be grown in a 2' x 2' area, but you have to keep them in their alotted space. I use upside down tomato cages to do this, and it works well for me...

EG

Ok I get the genreal idea now. the north side of the garden is only 6 ft wide. The west side is 12 but it gets sun all day regardless of direction. Ty for your guys help and any suggestions will help.
Spagettii squash if i put it at the end of the twelve feet it can grow rampat down the rest of the 20 foot garden got told it wouldn't matter.