Voice notes stem direction, bass line with score

[Kevin Tough]

Hi all/Claudio.

I've put this code into Lilypond...

\version "2.18.2"

\language "english"

\header {
    title = "Alternating Bass with Walk"
    composer = "EwithM"
    subtitle = "With pick or fingers"
}

\paper {
    ragged-right = ##f
}
\layout {
  indent = 0.0\cm
}
<<
  \relative c {
      \clef "treble_8"
      \key g \major
      \time 4/4
     % \partial 8 d8
        <<{c2 e}\\{r4 <a c e> r <a c e> }>> | 

      \bar "|."
}  
>>

The bass note stem direction is up and the rests are printed below the
half notes. The quarter note stems go downward. Can the stem direction
be defined per Voice and then would perhaps the rests be printed on the
staff? Voice one stems down and voice 2 upward????  As it is it is not
very readable.

Namaste,
Kevin Tough