Wow, you gave me some homework!
Thanks for all your input.
Most of the models mentioned are around the typical 1.5" (±0.1") from rail to scope saddle.... — so not really LOW (and excluded from the list below, unless they had something special to offer).
Here's the collection so far. Still open for more suggestions!
Matthias
The manufacturer
AD is a bit stingy with details of their mounts, but finally I found a specs sheet (the one that is really lower is not cantilevered, so no joy) (cf. image):
$40:
UTG Accu-Sync Cantilever Mount (No. AIR31834):
1.30" low | Cantilevered 2", or 1.4" | in 3 colors
$260:
Nightforce is stingy with info as well, 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, everything is rather confusing]
$135:
Burris AR-Signature QD P.E.P.R. Mounts (no. 410352)
1.5" | Cantilevered 2.5"
QD
Elevation adjustable from 0 to 47MOA, in 7 steps, with inserts
205$:
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
$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
[later addition:]
$ 410: Spuhr (No. SP-3026)
1.26" low | Cantilevered 2.7" | only 30mm tubes
[later addition, I missed this one:]
$253: Bobro Extended Precision Optic Mount (add $15 for 34 and 35mm)
1.575" low* | Cantilevered 2" | Tube sizes: 1" | 30mm | 34mm | 35mm
0 or 20MOA**
QD (choose lever to be on left or right side)
Link:
https://www.bobroengineering.com/Extended-Precision-Optic-Mount_p_20.html $243: Bobro Standard Precision Optic Mount (add $15 for 34 and 35mm)
1.42" low* | Cantilevered 1.7" guessed | Tube sizes: 1" | 30mm | 34mm | 35mm
0 or 20MOA**
QD (choose lever to be on left or right side)
Link:
https://www.bobroengineering.com/Standard-Precision-Optic-Mount_p_12.html * The Bobro webpage says: "Height: 1.420" from top of 1913 to tube center." For the Extended mount: 1.575" ➔ Well, for which tube size is this true? I am going to assume it is true for the most common tube, i.e., 30mm, and so 1.420 isn't bad (1.575 less so). The mount base would have to be progressively lower if this same height applied to 34 and 35mm as well.
** Careful (unless I'm thinking this wrong): If you want mount your scope further forward with a cantilever mount, the MOA cant will work for you. But, if you want to mount your scope further backward with the cantilever, the MOA will work against you, you will have 20MOA less elevation adjustment available in your turret with a mount with MOA cant. In that case better buy a 0-MOA mount. | For this latter arrangement, only the Burris AR-Signature QD P.E.P.R. Mounts allow you to increase MOA cant because the 20 MOA cant is not built into the mount but is achieved with shims.
Matthias
Who makes LOW Cantilever Mounts (for both 30mm and 34mm tubes)? 
