Underwriting insurance is a strange art, only partly science, and the requirements different companies have, to assess the risk covered, can vary greatly. To answer the "no driver's license" question, you need an Independent Agency with access to many companies. The agency I knew in Montana had over 20 property/casualty companies with whom to write policies. There must be several large independent agencies in your state, and they can ask this question of dozens of companies quickly for you. Most companies seem to align driving a car with driving a boat, in determing your skill with dangerous vehicles, so you may have a real challenge, but some company out there will work with you.
However, your original question brings up a much larger question, which has affected me since purchasing my R-25. Namely, whether the insurance on the boat hull is more important, or the boat Liability insurance that comes with it in the normal package. Remember, if you sink your boat, but swim safely away, or are elsewhere, when it sinks, you've only lost the boat. But, if your boat rams another boat, or a marina full of boats, the damage to other boats and the people in them can potentially run into the millions. Either way, it's your Loss, and until it's settled satisfactorily, you will be responsible for the damages.
My problem was, I had $500,000. Liability on my Yacht Policy from Chubb, but my $1 million Umbrella from a second company wouldn't cover above the underlying $500K. Without going into why not, let me add that soon there was a further development. The Umbrella policy would not apply if I was in a "live aboard situation" (exact words they used in a letter declining to renew). Best to have all your Liability coverages with the same company, to avoid this kind of mix-up. And, for most of us, our Auto policy is the most expensive policy, so one may have to start by switching that policy to another company which will also cover a boat and offer an umbrella policy over all policies.
Basic Rule: Underwriters want you to have a home on land, where your initial Personal Liability is part of a standard Homeowners policy. Only then, can you get the extra $1 or $2 million Umbrella, which greatly expands your coverage at fairly small premium. If you own a Ranger Tug, you probably have some assets or net worth. To protect your retirement assets, for example, you need an Umbrella Policy for that once-in-a-lifetime large Loss-----that just might come from owning or operating a boat.
Like automobiles, boats are in motion in some very dangerous places. You may not intend to harm anyone else or their property, but, if you do, best have a large amount of Liability insurance. Oh, and yes, insure the boat hull, too, but that's not your big exposure.
