Just a couple of ideas to add to your considerations.
First, I would not plan on staying alive by being close to medical care. You could die with a heart attack while walking in a hospital hallway. You need to follow your cardiologist's recommendations regarding meds, exercise and diet. They are your best strategy to avoid dying from another heart attack.
Second, I would give up the idea of shipping an RV to Europe or anywhere else in the world. The cost is high and for the populated areas of the world there are fewer and fewer opportunities for using an RV. Forget the idea of using your RV as a cheap place to live while touring European cities.
Next, forget about long term changes in transportation and the move towards electric vehicles. Make your plans for the next 5 or 10 years and then worry about later if you are still live and active.
For touring the US, that AF and Ram are great choices, especially for boondocking. Since you have lived in a sailboat, you understand many of the basics. You need to conserve water and electricity and of course for electric needs you must have a solar system, decent batteries, and a backup generator.
Unfortunately you may have a truck camper with slides that need to be deployed in order to use it. That will greatly limit you in urban areas. My TC does not have slides. I can stop in urban areas and stay the night without issues by using a little common sense on picking places to stay. Even without "stealth" camping there are often great choices for visiting cities. You mentioned San Fran and NYC. I spent a month outside San Fran sleeping legally next to the golf course in Mill Valley and taking the ferry into the city. There are numerous areas to stay near NYC within range of trains and other commuter transportation. As an additional example, Washington DC is great for camping stays. Greenbelt National Park is within the beltway and a short distance from the Metro system.