You may be right. But there was a lot of stuff going on and
sometimes studies or comparisons are done for engines of the same power. The 16 cylinder engine/s that Tomo is proposing has 1/3 more power than the V-12 which makes things a little more difficult, Much like most people would not want to use the same weight crankshaft in a 36 liter engine as they would in a 27liter engine
assuming both engines were making the same power per liter.
H-S used a rather light crankshaft for a 36 liter engine (about 50KG) but then they were only getting around 900-1000hp out of the engine in it's 1930s forms. Sauer changed to an 80 kg crankshaft when they tried to get 1400-1500hp out of the engine.
Not only were they putting a greater load on the crankshaft with more pressure in the cylinders (more force on the piston per firing impulse) but they were running the crankshaft at a higher speed. Going from 2400rpm to 2600rpm is 8.33% faster but the rotational loads go up with the square of the speed (so do the loads on the connecting rods just from stopping and then going back in the opposite direction hundreds of times per second) so these forces go up 17.3%. Junkers was pulling a miracle getting the 213 over 3000rpm
V-16 also has a crank about 1/3 longer which means more flex and for torsion that extra 1/3 length can mean a lot with the last pair of cylinders trying to twist the crankshaft and then unloading.
Our intrepid engine designer can opt for the H-16 and dodge the V-16 problems and pay for it with the 2nd crankshaft/crankcase and came drives. It might actually not wind up that different as far as weight goes. I don't know. But there is no getting away from the increased frontal area. This aspect had greater and lesser importance over the years.
1919 and the 20s it didn't really matter what shape the engine was (mostly), This 60.3 liter X-16 engine was huge
View attachment 784235
Don't even want to figure out the firing order on that thing
But they hid it well two of these
View attachment 784236
Another Blackburn product so frontal area was not a consideration. Fuselage was over 11ft deep.
In the 1930s size of the engine became a lot more important. During WW II it became a little less so, with 1700-2300hp engines and the fuel to operate them the planes hade gotten larger and with added length and decent streamlining a fairly large engine could be put in a fast plane with good streamlining (Do 335, a 13.8 meter fuselage can hide a lot of "stuff").
An H-16 engine may have been very useful as a bomber engine even if it would have given the 109 boys conniptions.