A 6 ft or 8 ft cable may be fine. Test vs a 3 ft to find out if you even notice any difference. Bluejeans you can order by the foot once you find out the length you need.
Or try an external phono preamp and send it back if you hear no difference. Don't buy from TTL with only 14 day returns, may charge a restock fee, and lacks prepaid return shipping discounts. Most other stores should have 30 or Crutchfield.com has 60 day returns and low flat fee returns.
$149 Schiit Mani
$249 Hagerman Bugle very recent new improved model.