freebsd-update: to a specific patch level - help please?

Hi!

I was surprised when using freebsd-update, that there was no way 
to specify a patch level.

In my day to day, I need to ensure security patches are applied.

I also need to assess the impact of patches, and ensure 
consistency (ie. versions) in my environments.  This can take time.

Here's a story for context, please feel free to skip:

   We are planning to cut our 10.3-RELEASE infrastructure over to 
11.1-RELEASE before the end of the month, because it's EoL in 
April.  We updated and cut over our production load balancer 
March 6th (and patted ourselves on the back for being ahead of 
schedule), and within less than 12 hours, updated our backup load 
balancers.  Unfortunately, we're now on ever so slightly 
different versions (-p6/-p7), and we're not affected by the -p7 
problems.  This makes my eye twitch slightly, especially when -p7 
was the first patch of 2018.

   Now we need to upgrade our application servers, that are 
running our trusted code, and -p8 comes out.

   I'm nervous about just applying -p8, but I definitely want to 
upgrade to 11.1-RELEASE asap.

   After assessing the impact of -p8 on our infrastructure, I 
feel the security risk is relatively low in the short term (and 
we've waited this long anyway), but I feel the probability of 
introducing unintended side-effects is high, and want some time 
to test and asses.

/story

It would seem to me, for repeatable environments, that binary 
updates from FreeBSD that can be pinned to specific version are 
highly desireable.

I've gone ahead and created a patch for my use here:

https://github.com/derekmarcotte/freebsd/commit/009015a7dda5d1f1c46f4706c222614f17fb535c

(there's a 10.3-specific one here:
https://github.com/derekmarcotte/freebsd/commit/458879f36ae984add0ff525fb6c2765fcf1fba67
)

I'd be happy to open a PR, and to iterate and improve on this 
PoC, but if there's no support from the project, I'll keep it to 
myself.

I guess what I'm asking is, for these reasons, is anyone willing 
to work with me (in mentorship+commit bits) to add this feature 
(maybe not this particular implementation) to freebsd-update?

Thanks!
Derek