THEMA: General question about feedback in Maerklin

TOPIC: General question about feedback in Maerklin third rail H0

Hello.
Now I participate in making digital layout using  Maerklin H0 third raill system and choosing method of train detection.

OVERVIEW
There are plenty of methods of train detection. We know that Maerklin electrically joines both wheels of every axles of any car. Therefore, method which using ability of electrical connection left and right rails by maerklin car axles - the best one.
Advantages is obvious - This method allow us to detect any car without magnets, resistors or wires passed via train from ski of loco.  Detection is very precise, and begins from first(or last) axle in train. This allow us to have Bi-directional detection which is not dependant from ski position.

EXPLANATION and drawback:
If we ll use standart S88 ruckmelders (Viessmann5217 for example) we ll read instruction. Instruction ll suggest to electrically separate left and right rail and ll suggest to connect s88 GND to common rail and s88 inputs to separated block sections. If we ll do so -  we will loose current pickup from block sections rails, because it cannot supply enough current to loco due to high resistance. Therefore current pickup from remaining common rail will be not so stable as original one.

SUGGESTION:
CMOS S88 ruckmelders has 5 v power supply and 2.1v threshold. Therefore it's obvious to use 4-5V powerfull ZENER diodes, which can be connected between ground and every S88 input.  In this case we ll have workable S88 contacts and also ll have current pickup to loco via both rails.  The voltage from feedback rail will be diminished at approx 4-5 V, but 12-13V of DCC or MOT voltage will be enough to push loco from dust area.  Moreover, MOSFET transistors or blue powerfull LEDs are more effective than Zenner diodes, because they have more rough V-A dependance.


QUESTION:
May be there are ready-to-use s88 ruckmelders with this current passing property exists in stores?

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Thanks,
Vadim