Well, unless you invest non-trivial extra work, you're going to start showing up on grid monitoring and finally someone will drill down in problem looking for broken substation and find you doing exactly the things that caused the problems and the reason for it being illegal to "just hook up".
It's just that often in many places law lagged in ways of dealing with islanded operation, and semi-islanded cases (where you invest in serious gear to separate your local micro grid from external grid preventing the issues that cause technicians to show up and report you)
A disconnect isn't a huge deal, most houses have one but they don't have a lock-out position and that's a must for an islanding operation and you'll need inverters that are happy to produce power even when the grid isn't present. Those are not the norm, but you can buy them (I'd recommend Victron). You'll also need a fairly large battery to stabilize the whole thing, without a battery you'll see massive voltage fluctuations as the inverters try to adapt to load without the required low internal resistance backing, so I would definitely recommend against that unless you like buying new stuff every other week.
It's just that often in many places law lagged in ways of dealing with islanded operation, and semi-islanded cases (where you invest in serious gear to separate your local micro grid from external grid preventing the issues that cause technicians to show up and report you)