I want one of the reproduction trench gun versions, but I've heard the quality on them can be great or terrible depending on the batch they come from. My next option is to recreate a trench gun with a modern shotgun. The two options being the Mossberg 500 and the Remington 870.
Now, the 500 already has what could be considered the modern equivalent to the trench gun in the 590A1, which has a heat shield and bayonet lug. The problem is that while I have a version of the 500 (A New Haven with a variable choke barrel) I can't mount a bayonet lug, because unlike many other shotguns, the design doesn't allow a magazine tube extension, except for the models that already have one, with the 590 being the only one with a bayonet lug. While 590s aren't terribly expensive from what I remember, they aren't quite as cheap and common as the other variants of the 500 and 870. Adding just the heat shield and a slightly shorter barrel (Compared to the monster length bird hunting barrel that it has now) would be cheap enough, but the bayonet lug is the best part.
The 870 on the other hand does accept mag tube extensions, and ones with bayonet lugs do exist. The problem here is that the cost of the bayonet lug mag tube extension is almost as much as the cheapest used 870s out there. Granted the mag tube seems to be made to a high grade, justifying the price. As with the 500, barrels and heat shields are plentiful and fairly cheap, even for good ones. The problem here being that I don't own an 870, yet.
One downside to either of those is that it uses the same bayonet lug as the AR series rifles, meaning they use the modern bayonets as well. If you know the 97' and the bayonets of the time, you might know that a long and short version exist, with the long one being almost a short sword. Of course, high quality, usable as knives versions of either style are pricey. the OKC M9 bayonet is nice, and from what I heard, well worth the cost. Finding a quality usable reproduction of the old style is a bit hard, but I hear they're out there. Of course the solution around all that is just make a custom bayonet. I know knife making, and I could either mount the new blade in an old handle (Plenty of old bayonets with chipped, broken, and abused blades out there) or I could also make the handle and locking mechanism from scratch fairly easily.
Since your pic is of the normal 97' and not the trench gun variant, I'll post some pics.
There was also a takedown version (a gun that can be taken apart for easier transport) of the 97", which I don't think is very common in shotguns. I used to have some pictures of one with a custom case made from a violin case or something, gangster style.
Aside from all that, and making a long post even longer, I want to mention how that despite their name, combat knives (bayonet or otherwise) rarely get used for such. Most often they get used for the same things a pocket knife get used for; cutting rope, opening a box, and so on. In fact, I'd say kitchen knives probably see more blood than combat knives, and I don't mean cutting meat. I don't know for sure, but the number of deaths by knife both in military combat and among civilians is probably not just higher in general by number of knives of said type, but also proportionally to the number of each. I wouldn't be too concerned about the guy with six Ka-Bars on his belt, but that chef over there looks shady as fuck.