Yeah you basically need an industrial machine or the like.
Well worth the $ if you are going to sew leather, convertable tops, canvas or anything heavy.
I ended up with a thompson mini-walker mostly because it was cheap and portable. Its got a shallow throat and its difficult, but portable and that is what I wanted.
I never saw the need to drop $1000 plus on a Juki until I sat down at one in a friends professional shop. Geez are those things smooth.
Difference is like between a 1965 VW beetle and an new Cadillac.
At any rate with my little mini-walker, I did a convertable top and the interior for 2 cars, both out of leather. Also did a pool cover out of acrylic stayfast canvas for my brother in law.
You can work with a short throat you just have to pre plan your assembly to keep the thickest bulkiest part on the outside. Eventually you will have to pass a bulk throught he middle. Hopefully not too bad and you can roll it and shove ti through. A real PIA.
Years ago, like in 1980 I did a vinyl interior for a car with a normal sewing machine and I would not recommend it.
Very frustrating. You need enough power to go through thick fabric easily and smoothly.
Here you go, juki America.
If I was doing it again, I would look for a used Juki.
One on craigs list. This is what you need. Actually if I were going to build tents car/boat interiors or something like that I would be on it. I dont think these machines will bar tack and do some of the other normal functions. Not 100% on that though.