PWM without HDMI into RPi

I'm using the PWM setup and have run into the issue where it only works when there is an active HDMI connection into the raspberry pi on boot.

I read that if you use Jessie or Jessie-lite, the issue doesn't exist. I'm using Jessie (Pixel) and ran through the installation. In the end, I still need to have an HDMI connected to the RPi. If I don't have it connected, it works for about 5 seconds before it freezes up.

What approaches are there to fix this? Other considerations.

1. I'd rather not use an Arduino. I came from that setup, and don't want to go back to an extra chip if possible.
2. Happy to use the WS281x-SPI driver, but everytime I startup the RPi I have to figure out what the proper rate is. It seems to change after every reboot.

To be honest I'm a bit afraid to venture that deep into depths of the RPi...I'm not a novice, but far from an expert so clock type stuff scares me. Let me check out that thread to see if I can disable the analog audio before trying SPI again.

Really appreciate the tips!

And problem solved. Per Gadgetoid, the following worked perfectly:

Try adding the following to your /boot/config.txt

hdmi_force_hotplug=1
hdmi_force_edid_audio=1