That type of work is too infrequent for most companies to justify hiring a dedicated developer. You should work for a system integrator if you want to do that

That type of work is too infrequent for most companies to justify hiring a dedicated developer. You should work for a system integrator if you want to do that kind of work with regularity. The integrator contracts you out to those companies as needed, and you develop a niche and maybe customers start asking for you by name. In the best cases the integrator is your employer and offers full benefits, as well as absorbing the costs of downtime. That business model can also be abusive for obvious reasons. I can recommend a good company if you're interested.