You get user certificates from CILogon but you also need host certificates.
You looked over the list of IGTF CAs but they don't meet your needs.
Why not use the Let's Encrypt CA?
How do you set up /etc/grid-security?
Getting your host certificate
Follow the Let's Encrypt Getting Started guide.
For example:
git clone https://github.com/letsencrypt/letsencrypt
cd letsencrypt/
./letsencrypt-auto --debug certonly --standalone --email human@example.org -d example.org
# cert in /etc/letsencrypt
# then before it expires...
./letsencrypt-auto renew
Setting up /etc/grid-security/host*.pem
ln -s /etc/letsencrypt/live/*/cert.pem /etc/grid-security/hostcert.pem
ln -s /etc/letsencrypt/live/*/privkey.pem /etc/grid-security/hostkey.pem
chmod 0600 /etc/letsencrypt/archive/*/privkey*.pem # ugh!
Setting up /etc/grid-security/certificates
git clone https://github.com/cilogon/letsencrypt-certificates.git
cd letsencrypt-certificates/
make check
sudo make install
Like other Internet CAs and unlike IGTF CAs, Let's Encrypt issues end entity certificates with subject DNs outside a controlled namespace (i.e., "/CN=*"), so the signing_policy file is not enforcing a strong namespace restriction.
Let's Encrypt does not issue CRLs for end-entity certificates (see the Certification Practice Statement).
Make sure to have a process in place to renew your certificates (e.g., Certbot).
# hostname
example.org
# grid-proxy-init -debug -verify -cert /etc/grid-security/hostcert.pem -key /etc/grid-security/hostkey.pem -hours 1 -out /tmp/hostcerttest
User Cert File: /etc/grid-security/hostcert.pem
User Key File: /etc/grid-security/hostkey.pem
Trusted CA Cert Dir: /etc/grid-security/certificates
Output File: /tmp/hostcerttest
Your identity: /CN=example.org
Creating proxy ......++++++
.....++++++
Done
Proxy Verify OK
# openssl verify -CApath /etc/grid-security/certificates /etc/grid-security/hostcert.pem
/etc/grid-security/hostcert.pem: OK
# if [ "`openssl x509 -in /etc/grid-security/hostcert.pem -noout -modulus`" = "`openssl rsa -in /etc/grid-security/hostkey.pem -noout -modulus`" ]; then echo "Match"; else echo "Different"; fi
Match
# openssl x509 -subject -noout -in /etc/grid-security/hostcert.pem
subject= /CN=example.org