I still wonder about Config, though.

It's quite easy to change %Config values - and the same method works on all systems.
Just create a file named (say) New_Config.pm:

package New_Config;
use Config;

my $new = tied %Config;

$new->{make} = 'dmake';
$new->{byteorder} = '43215678';
# Specify as many as you like
1;
[download]

Then you'll see:

C:\>perl -V:byteorder
byteorder='12345678';

C:\>perl -MNew_Config -V:byteorder
byteorder='43215678';

C:\>perl -V:make
make='gmake';

C:\>perl -MNew_Config -V:make
make='dmake';
[download]

The first I became aware of this was with Mattia Barbon's EU::FakeConfig.
This was very useful as it allowed the use of gcc toolchains to build and install XS modules on perl's built using an MSVC toolchain. (This was back in the day when ActiveState were providing perl's built using MSVC-6.0.)

I haven't checked to see whether this technique is utilised by Strawberry Perl in achieving its relocatability.
IIRC, on Windows some Config keys can be altered by editing Config.pm and Config_heavy.pl - but there are also keys that, to my knowledge, can only be changed via this "tied hash" approach.

Cheers,
Rob