Hi Gary,
No, the twelve volt hair driers are not going to "do the deed".
Three 12 volt wired in a balanced manner will be adequate. (and better than 4 six volt jars).
I'd go with the Xantrex prowatt from bestconverter.
http://www.bestconverter.com/Prowatt-SW2000-Sine-Wave-Inverter_p_375.html#.W7qcKBFRe1sThe inverter needs to be as close to the battery bank as humanly possible without being in the same compartment. Use the biggest meanest wire that will fit (welding cable is good).
Be aware that the prowatt line is a "throw away" if the magic blue smoke is let out.
On the 120 volt side, I'd put an outlet in the kitchen, and another in the bathroom.
garyhaupt wrote:
Looking at hair dryers for RV'ing..there are 12v plug-ins...? Do they do the job? Gary