After long experimental sessions with the tablet I discovered more good reasons to use the tablet in my remote station. The background why I did long tests is the circumstance I can only use 12 V solar power and need a low Ah consumption gear.
As I mentioned the other day listening and recording with the ELAD FDM-SW2 software was only possible with a limited bandwidht set to ~192 kc/346 kc, which is beyond my needs. The ELAD FDM-SW2 software consumes more resources than the tablet could provide. Recordings stuttered. Now I was testing the Studio 1 software and was able to record and listen stutterfree with ~1500 kc bandwidht. This is enough to record the whole MW Band e.g.
So my complaints are now going to the software developers. Studio 1 is fine, lets say very fine, but not able to record automatically at a certain time, ELAD FDM-SW2 does but is not able to record ~1500 kc bandwidht.
Another issue with the tablet is that it connects only through USB2 (and not USB 3) with the ext. HD. At some times the audio hangs for 1-3 sec. which does not affect the recording in most of the cases, but in some. The tablet can use a 128 GB microSDXC-Card which could be much more faster. I did not test this now because I need more than 128 GB of space.
As I wrote the other day recordings and listening through the HD are possible if connected through a USB-Y-Cable to a seperate batterie charger.
The Trekstor Surftab is not so bad as thought here. It is suitable to run the station.