Has any Buddhist meditator claimed that the mano-vijnana has a base to differentiate it from the other consciousnesses?
According to the Theravada Abhidhamma Mental Consciousness (mano-vijnana) is heart based. This is what Buddha realised through his meditation. Other consciousness arise with the respective faculties and the base, e.g. eye-consciousness with the eye.

It is suspended when you are in Nirodha Samapathi and in Bavanga consciousness. Also perhaps in Pala Samanapathi if this result in a momentarily entering Nirodha Samapathi but not very sure on this as there are different view on this.