I also did my first large quilts in a 16" hoop and I didn't have problems to handle it. I sat in a comfortable armchair and the quilt laid on both sides on the armrests. I heard of other hand quilters that they spread the quilt on a large table and sit on one side to quilt.
When you use a hoop it is necessary not to put the quilt too tight in it. It should be a little loose and the needle can be moved easier.
I am sure you already know that hand quilting needs practice - you will find your way!