I agree it would be better to patch the script. However you don’t have to
make the package multiarch-compliant; you can install your library in a
package-private directory, the same on all architectures, and leave it at
that. That said, given that i386 libstrangle would be useful on amd64,
alongside amd64 libstrangle, it might be better to look into the Rpath token
expansions which are supported by ld.so in LD_PRELOAD, e.g. $PLATFORM —
although it doesn’t fully match the multiarch requirements. (See man ld.so
for details.)