Whilst I would also not recommend buying a boat sight unseen, I have just done it, primarily due to COVID and the restrictions around travel that let us no real option but to find as much information as possible and use bucket loads of common sense and a fair bit of time...
We purchased Maya, our JR Schooner Maurice Amiet Spray Steel Junk Rigged For Sale, 12.00m, 1987 (boatshed.com) just after Christmas and didn't physically get to see her until mid February! I have to say my experience with the surveyor left a whole lot wanting, but she has turned out to be an exceptionally good purchase for us.
She is actually a "Metamiet" Embrun 40, of which I have now found a few examples, none JR but all in Steel, some professionally built and others home built (as Maya was) but the caveat being with Maya was that I had seen the receipts and photos of the work undertaken under a tent in Mallorca over 18 months, it was nearly 6 figures and the entire hull (except the keel plate, which is 22mm thick) was shot blasted back to bare metal, well repaired, professionally painted and copper-coated.
I am also fairly lucky that the interior was well photographed and I knew how much of a project that would be. The only "surprise" we had was water and fuel tanks... she had fabricated stainless tanks and I thought the water tanks might need replacing, just to know the water was drinkable (they were the original tanks and nearly 30 years old...) but the fuel tanks were by far the worst, the shot blasting grit had got in through the sole and part filled the sides of the tanks deep in the keel, this had got wet, I think from rain coming in the mast partners whilst she stood for nearly 2 years and this rotted the tank sides and base, the full diesel tanks had also got diesel bug, which was polished and has now been used in the crossing from Italy to Spain! The water tanks had done the same so all were fabricated and replaced.
The only other thing I partly expected and it had happened was that the original solar panels had given up and the house batteries had discharged to such a point they could not be recovered.
Otherwise everything else turned out to be exactly what I thought it would be and need the work I thought it would need... I am lucky to be a diesel mechanic and pretty practical, so knew that as the hull and decks had had all that work done, everything else would actually be pretty easy and "cheap" in comparison!
The advice I would give if you are thinking about buying sight unseen (and like I said I wouldn't recommend it!) is: (This probably wouldn't apply to a lower value boat you might not ordinarily survey)
1. If the boat is as close to your ideal as you think, make an offer "subject to survey", you'll own the survey once it's done and can sometimes onsell it to the seller (with the surveyors permission) if you choose not to go ahead The survey also gives you negotiating leverage, but only share key points, not the actual survey.
2. Give the surveyor very detailed instructions as to what you feel you want to know. Make a list of specific questions you want asked, the survey might cost you a little more, but if you can't get eyes on, it's the next best thing!
3. To assume the worst after the survey and make an offer based on that, that could then be the starting point for negotiations with the seller.
4. If it's a reasonable sized boat like Maya, build into the offer the cost of replacing most things, like water pumps, batteries, running rigging etc etc. The only thing the seller can do is say no or otherwise negotiate.
5.. It's a boat, be prepared for all that work :-)
I've attached a load of images as a sample of what I have (it was nearly 600 photos from the previous owner)
It took me about 8 weeks to make her seaworthy (mainly running rigging, safety equipment, electrics and plumbing with the tanks) and she took us safely across the Med in 5 days, from Spain to Northern Italy, I am now finishing the interior whilst she is only 2 hours drive away as opposed to 20 hours away!
Ultimately it was a risk, but I also knew there was +/-12 tons of scrap steel and a good quantity of lead ballast plus a good engine and a load of fixtures and fittings that I could have got good money in scrap for... but very glad it didn't come to that!