What size hoop are you using? I use a hoop that is pretty big.... about 18"x28" oval. I can't imagine using anything smaller.
I lay out my quilt and pin the sandwich together....pins are maybe 4-6" apart. I have used the spray that holds the sandwich together but I've found that if I use too much, the needle doesn't want to go through it or gets sticky. I start in the middle and work out. It is still difficult to keep it super smooth for me with a hoop..... no hoop wouldn't work for me, I don't think.
I now have a quilting frame that is probably 8 feet long and about 20" across. That works best for me. It's a home-made one that I bought at an auction years ago. The quilts that I've done on the frame are my best work. It isn't large enough for a king but anything less than that will work. I could post a picture of it if you have someone that could make you one.