Thanks for the input.
I'm publishing the list of what I have found so far.
Please, do not be offended as I was at some of the prices, both high and low....

Some of these are made to withstand 50cal recoil perfectly, because lives depend on it. That kind of justifies the price....

Most of the lowest mounts I found got as low as 1.5" (±0.1") from rail to scope saddle.... — they are easy to find so I do not even mention them in this list (unless they had something special to offer).
Still open for more suggestions!
Matthias
LOW Cantilever Mounts (30mm/ 34mm)

$40:
UTG Accu-Sync Cantilever Mount (No. AIR31834):
1.30" low | Cantilevered 2", or 1.4"

in 3 colors
At 10 times the price of the UTG:

$ 410:
Spuhr (No. SP-3026)
1.26" low | Cantilevered 2.7" | only 30mm

$260:
Nightforce is stingy with info, no diagrams anywhere to be found....
1.125" or 1.036" low* | Cantilevered 2" and maybe 3" — this is just a wild guess
*[website contradict each other, the model naming conventions are rather confusing]

205$:
GG&G SOCOM2 Accucam Quick Detach Mount:
Can someone confirm the low height of only 1.26"...? The photos don't seem to support that....

1.26"??? | Cantilevered 3"

QD

$350:
Geissele Super Precision Mount
•(no. 05-500B):
1.35" | Cantilevered 3" (guessed)
•(no. 05-494B):
1.35" | Cantilevered 2" (guessed)

$254:
SIG Alpha3 Mounts (SOA30001)
1.375" low | Cantilevered 2" (wild guess) | only 30mm tubes

$135:
Burris AR-Signature QD P.E.P.R. Mounts (no. 410352)
1.5" | Cantilevered 2.5"

QD
Elevation adjustable from 0 to 47MOA, in 7 steps, with inserts

$42: Remarkable because it's a fairly low 2-piece cantilever from
UTG from the Accu-Sync Cantilever Mount line (No. AIR322S):
1.46" low | Cantilevered 1.5"

in 3 colors
2-piece