Dear Nicolas,
I have same setup like you want to do while my plane configuration is same as yours Servos, YS170DZ and Power Box DIGI switch and TP1320 Lipo pack. YES, I did solder another cable in parallel to Lipo cable in order to attach to it an outside testing port for load testing prior each flight. Also I did it to have the option to filed charge with no need to remove the pack from the plane.

My LiPO pack is installed under the ballypan and I opened the ballypan in away that I can switch the pack at the filed without disassembly the ballypan or the wings.

In real life I never fly more the 5 to 6 flights a days and thus with this setup I never needed to recharge at the filed or to switch battery.
Although I have the option to charge the pack while it is inside, when I finish my flying, I disassemble the LiPO pack and I recharge it while it is NOT connected to the model.

I also found that the LED indication on the digiswitch is solid and reliable. Before each flight I turn on the model and move all the sticks simultaneously. If during this test the LED stays green and do not turn momentarily to Orange, it means that you can safely depart and make P09 and F09. Finally Switching to this setup I save about 60 grams from the model.

Have fun and good luck.

Amram Leshed
F3A Israel

*** In the picture you can see the two pilots which will be with you in Italy - Left: Shlomi Chester and on the Right Ohad Zarko