Have you checked around for a store that rents out their longarm? Usually, they require a class to learn how to use their machine and certify you to use it, then you can rent the machine.
I have quilted on my domestic machine and rented the LQS LA until we moved and had room for me to get a LA.
That said I had FMQ classes by Elizabeth Spannring, Diane Gaudynski, and Sue Rasmussen, who all do their quilting on domestic home machines and do large quilts.