"An Iowa would need as many as a carrier group and even with the newest fuel, she still smokes like a locomotive, making her an easy target."
The Iowa or any oil powered ship does not make smoke. Look at any picture of an Iowa class or any other oil fired ship and you see no smoke. The only visible smoke that ever came out of stack came from a coal-burning ship. An oil fired ship can make smoke to create a smoke-screen for stealth purposes if it needed. Oil fired boilers came out during WW1 with the benefits being greater power, easier to refuel, easier to run and no smoke. No smoke made it harder to see one's enemy coming over the horizon. It is also made it easier to see in a sea battle. Coal fired smoke was so heavy during the Battle of Jutland it was nearly impossible for the admirals to signal their fleets or see targets. The British had a few oil fired ships at this battle and the advantages were clearly seen.
"To put a battleship to sea today would mean various companion vessles, tenders, submarines, etc for supply and protection"
That is required with any navy anyway, so your point is moot.
Any oil fired ship makes smoke, especially on cold fireup. I have put fuels of every specification aboard US & foreign ships as well as the newest Navy destroyers. Every liquid hydrocarbon throws off soot when burned. The days of standing off shore and lobbing shells 15 or 20 miles inland is over, especially in Asia.