I'm not sure if this is anything like what you are aiming at. It uses a global match to find the whitespace positions then substr to divide the string.

knoppix@Microknoppix:~$ perl -E '
> $str = q{one word  two spaces    four   spaces one};
> push @posns, [ $-[ 0 ], $+[ 0 ] ] while $str =~ m{\s+}g;
> say qq{@$_} for @posns;
> # Split string at fourth gap.
> $left = substr $str, 0, $posns[ 3 ]->[ 0 ];
> $right = substr $str, $posns[ 3 ]->[ 1 ];
> say qq{>$left<};
> say qq{>$right<};'
3 4
8 10
13 14
20 24
28 31
37 38
>one word  two spaces<
>four   spaces one<
knoppix@Microknoppix:~$
[download]

I hope this is helpful.