If by a "Splitter" you mean a cheater box.. Those are not all that useful (This is a box that lets you plug in a 50 amp cord to two 30 or 20 amp outlets, it's also a GFCI tester as it will trip a GFCI 100% of the time, making it next to useless)
A DOGBONE connector (30 amp plug and 50 amp outlet) from your local RV store, Camping world or Wal-Mart will feed BOTH legs off a single outlet. You may need 2 of them
one 50 to 30 one 30 to 15 Though I have, on rare occasions, seen one that goes all the way from 50 amp to 15.. Kind of rare though.
Home is where I park it!