TVS with low Vclamp margin
Any tip will be welcome.

The only way I see to solve this is to identify the specific parts in the PCB (currently not shown in the question) that are most likely to be victims to the over-voltage and, assess what protection is really needed to prevent those devices failing. Having a continuous specification of 17.5 volts maximum will almost certainly mean that a transient limit of several volts higher than this is likely for well-designed equipment.
So, at the moment, there is too little headroom in your requirements even for a zener to be a solution let alone a TVS. I suggest you analyse the PCB to see at what point a higher voltage (transient) might become a problem.

Long cable runs and hot plugging could induce transient voltage spikes
which may exceed the input voltage limit and I need to protect it.

It's generally accepted that the worst case scenario will be when you activate the power supply at the source end of the cable. Due to transmission line effects, you might see a peak (at the PCB) of up to double the applied source voltage.
You also need to calculate the transient energy that can flow from the source too so that you can pick a TVS diode that can handle the transient energy without failure.
It's all about threats and victim analysis.