Elder. *sheesh*!
Anyway,
I thought long and hard before deciding that was a k suffix. You are right about the camera angle and lighting, also it looks like it may have been poorly stamped. To my own eye it has more of the characteristics of the k than the h . In addition, the picture you took of the trigger plate edge numbering shows the suffix at an extreme angle, and the "break" in the short stroke visible from that angle gave me confidence in my interpretation.
In addition, an h suffix would be an anomaly on this pistol.
Many Commercial Lugers were WWI military guns, often with their chamber dates and military proofs ground off, sometimes replaced by civilian proof marks (the Crown/N). However, the serial numbers on the small parts are stamped on the faces of the parts--on the visible surfaces, for example, of the trigger plate and takedown lever.
Your parts are stamped in the "hidden", Commercial fashion. This tells me that the Luger was newly-produced as a Commercial weapon.
When DWM began to stamp Commercial Lugers in late 1920 with letter suffix serial numbers, they started with the i suffix (and ended with the v suffix in 1930). This is the letter suffix equivalent of 92000, which is where the 5-digit Commercial serial numbering ended. I realize this is confusing; Luger serial numbering is a complex topic worthy of its own explanation. This fact, however, is sufficient to explain my conclusion.
Since Alphabet Commercials started with the i suffix block, they will not be found with the h suffix. The rest of the characteristics of your Luger are entirely consistent with 1920s-era commercial production, and do not, at least in the views you provided, have any characteristics otherwise. Therefore, the letter stamping must be k .
By the way, you are to be complimented on your detail photographs, and you have a really nice ensemble and a Luger which you have done very well by, both in your attention to it and you purchase price.
--Dwight