what are the advantages/disadvantages of steel hullled as opposed to aluminum hulled vessels.
Sorry your question turned into a collection of sermons about everything but hull material ...
An owner/operator can maintain an 80 foot metal boat. It is not easy, it requires skills that many (most?) people probably lack but are perfectly capable of learning.
It is common for a crew of 2 to maintain a 100' boat to a very high standard. They do it by contracting a lot of the labor (day worker help to varnish or wax) which allows them to concentrate on routine cleaning and upkeep. It is a full time job though, make no mistake about that.
Most 70 or 80 foot boats sit un-crewed and unattended all week (or for weeks on end) and don't suffer any great insult. Boat fanatics love to claim the boat would sink or fall apart in days if they were not such magnificent mariners and watched it every moment.
Now, to your steel or aluminum question - steel is very easy to repair and perform paint touchup. The problem is not the steel you can see, it is the steel where you can't see it. Standing water between frames in places that get no ventilation and you can't see it will corrode quickly and eventually destroy the boat's value. It can be repaired easily but it is expensive to haul and crop bad steel then replace it and repaint it. Steel is strong, you can easily modify the hull and superstructure if you want to learn to weld and finish.
Aluminum is also strong, relatively corrosion resistant, but it has its own problems. Exterior paint is a pain, a little scratch will allow corrosion to form bubbles under the paint that must be quickly repaired or they will spread rapidly and look terrible. They do cause damage but it takes time. Ugly is not necessarily dangerous. The good side is uncoated aluminum is generally very corrosion resistant (that is why you see so many bare aluminum workboat hulls) and the problems with standing water in the bilges and hidden places are not such a big deal with aluminum.
You can learn to weld aluminum just like you can learn to weld steel. It just takes different hardware and techniques but any reasonably adept individual can learn it quickly. As a matter of fact, welding aluminum with a spool gun may be easier than welding steel with a stick for many people.
There are as many aluminum boats as there are steel boats. Different strokes for different folks and all that. Larger yachts might have a steel hull because it is cheaper, and an aluminum superstructure because it is lighter. So there, you get both materials on the same boat.
Try and ignore the naysayers. It's your dream, your plan, and your own life. Go for it.