California license class C-4 and air to water heat pumps

I know the CSLB is the only place to ask for a conclusive answer but that's not that easy. ( California State License Board ) If you're not reporting a violation or checking up on a contractor or are an applicant trying to get a license, there's not an obvious point of contact. In fact there's little there for a licensed contractor but to pay, by snail mail of course.

My understanding is that the C-20 HVAC license and C-36 Plumbers license are the approved classes to install air to water heat pumps in CA. I think mono-blocks only for C-36. CA Plumbers are not allowed to service or install anything over 200,000 BTU input combustible fuel. A C-4 is needed for anything over that size. Seems odd to give C-36 HP water heating approval but not C-4 when water heating is precisely what a C-4 contractor does.

This is the CSLB's C-4 class description from their website:
A boiler, hot-water heating and steam fitting contractor installs, services and repairs power boiler installations, hot-water heating systems and steam fitting, including fire-tube and water-tube steel power boilers and hot-water heating low pressure boilers,steam fitting and piping, fittings, valves, gauges, pumps, radiators, convectors, fuel oil tanks, fuel oil lines, chimneys, flues, heat insulation and all other equipment, including solar heating equipment, associated with these systems.

"And all other equipment ......, associated with these systems." This seems like it might be open language that includes heat pumps.

I'd like to be able to offer my customers permitted air to water heat pumps without debate at the different authorities counters. There's 38.8 million people in California and from my estimating/ guess there's somewhere around 3,500-4,500 C-4 license holders and less that are currently active. Many who have C-4 hold the C-36 as well. Sole C-4 contractors are not a big lobby.

I got my universal EPA certification in 1998 and have done years of service and installation for HVAC contractors. I own all the tools. I have the experience to test for the C-20 license if it comes to that but I don't want to do HVAC or Plumbing for that matter.
Some permit officials have no issues and others, in the next town over, flat out refuse me as heat pumps are not called out specifically in the CSLB C-4 description. Fair enough, they are just trying to be good at their gate keeping jobs. The very same person lets a C-36 install a 400,000 BTU water heater because they can't find anything about a commercial size limit.

One official had no idea what a C-4 license was. He had to look it up and was still confused. He went on to straight face inform me that, his ignorance is good evidence that there are no boilers in his city. Great deduction Watson!

In another case I found a near by C-20 HVAC contractor with "Hydronics" in his legal name installing and servicing boilers and radiant floors with permits. Funny because I had to appeal to CSLB higher up's to convince them a C-4 contractor is by definition a hydronics contractor for them to give approval for "Hydronics" to be in my company name.

It would be just like a bureaucracy to say heat pumps are the future, began to mandate them out of one side of their mouths and then limit the ability of commercial water heating contractors to install them with the other.

Anyone have any knowledge on the topic before I start digging at CSLB? Does your state have a similar C-4 license class? Who's allowed to air to water HP? I'm hoping I've just missed a little known memo that includes C-4 in the water heating heat pumps game.