Unless you are dead set on owning a straight tail you should expand your search to include v-tails. I would wager that most pilots could not tell which tail was behind them in flight and in many cases the CG loading can be more favorable.
Care to elaborate? All kinds of non-stc/PMA/other letters have been plugged into cigarette lighters over the years. Aviation-centric companies sell USB power adapters. The connection is certainly temporary in nature.
That will certainly work, just have a decent chance of getting a noise on the intercom/radio. I had to audition a few cheap ones until I found something that worked well enough. Seems there are some reasonably priced ones these days that seem to be tailored at aircraft - hopefully they are quiet.