Adding space between chord glissandos

[Caio Barros]

I'm writing a part for 5 violins in divisi in which they make a glissando and I want to add space between the two chords because the accidentals make it looks to confusing.
Using \override NoteColumn X-offset doesn't seems to work because at least in version 2.12.3 I need to add hidden voices to make glissandi in more than one note.

this is what I got so far

\version "2.12.3"

\relative c' {
  << 
    \time 5/4
    {\tieNeutral <des ees f g a>1^"con. sord." ~ <des ees f g a>4 ~ \time 7/4
      <des ees f g a >4\glissando \mf \< %{I WANT TO ADD SPACE BETWEEN THOSE%} <c d e fis gis>2 ~ <c d e fis gis>4. \breathe <c d e fis gis>8^"pizz." <c d e fis gis>2:16  \glissando ^"arco" 
      <des ees f g a>2.:16 \ff 
    }
    \\
    { \hideNotes s1 s4 des\glissando c2 s2 c \glissando des2. } \\ { \hideNotes s1 s4 ees\glissando d2 s2 d \glissando ees2. } \\
    { \hideNotes s1 s4 f\glissando e2 s2 e \glissando f2. } \\ { \hideNotes s1 s4 g\glissando fis2 s2 f \glissando g2. }
    
  >>
}