Growing pumpkins and squash on unimproved land (ie, tall grass/fence line)

I absolutely LOVE pumpkins and squash, but I am just not going to have room to put them in my garden--not with the 6' or so required.

I watched some youtube vids of people "crimping" a rye cover crop, and planting pumpkins on top of that without tilling.  

There is a strip of about 6' between the lawn and a field (no idea what the farmer will put in there this year).  The strip is just tall grass.  

I was thinking I could dig a planting hole for the vines (larger than needed, mixed in with some compost), then mulching around it with cardboard, and adding cardboard as the vines take off.  If it would work, at least the plants would not have any stress due to over crowding.

Does it sound like a viable plan?  I could use a string trimmer to flatten everything at the beginning, then keep choking the grass out with cardboard mulch as the vines developed.    

I'm fairly novice at veggie growing, and I had no idea these plants required THAT much space--but the 6' strip of tall grass is at least 200 yards long.  If I could press it into service, that would be ample space.
Thanks for any suggestions.

Now that I think of it, maybe I could dig the hole by cutting out the sod in a kind of plug, dig the hole, then put the sod upside down in the bottom and backfill with soil and compost.  That would at least kill the grass in the immediate vicinity of the roots of the squash and pumpkins.

I've had pretty good luck with setting a flattened box on grass, wetting it, pouring a bag of compost on top and planting four winter squash seeds near the center/top. The roots dig through the cardboard OK by the time they get down there. I think the approaches you're looking at will work , but you might get away with even less work.

Go to a local farm, or feed supply store, and get several bales of moldy/old/last year's hay. Put the bales where you want the squash and make a pocket in the hay and fill it with good dirt/potting soil/compost. Whatever is handy. Plant seeds in the pocket dirt. Water the bale well, and keep it watered throughout the season. You'll have a good crop of what you plant. The following Spring break up the remains of the bale and add to compost pile.

It can work. I often have squash/pumpkins overgrow the garden into the surrounding grass. The only problem is finding all the hidden fruits. An area around the seed, at least a few feet, needs to be weed-free. Beyond that, let them grow! A fence-line is a great place to grow squash.

I've planted pumpkins in a shovelful of manure and compost in a patch of weeds or grass and it almost always turns out better than the ones I plant in a tilled and irrigated field. Sometimes I'll put a piece of cardboard down first but sometimes not.
The first time I did it this way was when we lived in a rental with a tiny yard and my toddler had a pumpkin seedling she planted at the spring fair. I put a bag of compost in the corner of the fenced lawn and just kept moving the vines so they only grew along the fence so none of the lawn would die. She got 3-4 good sized pumpkins from that one plant.

A few years ago my kids got those tiny growing kits with the impossibly tiny pots for sunflowers and pumpkins. They started one seed each in those tiny pots and then I didn't have room in my planned garden for them so we stomped down the weeds by the road, put down some cardboard with a hole cut in the center, dug a small hole that we filled with compost and planted each seedling. I didn't have much optimism for those plants but each kid grew one beautiful pumpkin and one beautiful sunflower that year with minimal watering. 🤷 How does this work so well- 100% success versus my sunflowers and squash vines that get eaten or suffer transplant shock and I have to plant 10xs more plants and seeds to get any pumpkins and sunflowers.