After the trouble with haveng crashing and coredumping, I have switched to rngd. I noticed that the default options for the RPi could likely use some sane defaults given that the hardware number generator is available, and it just does not make sense that the average user is not trusting is. I would suggest something in the following direction.
/etc/conf.d/rngd
RNGD_OPTS="-x tpm -x jitter -x nist -x pkcs11 -x rtlsdr"
