Having lots of trouble trying to understand how to play rest strokes (and yes, I've used the search function

).
I'm using the floating thumb technique, and have my thumb resting on the string below the one I'm playing (D if I'm playing G, A if I'm playing D, resting on the pickup if I'm playing E).
Are rest strokes still necessary for muting in this case?
Since my thumb's already on the string below the one I'm plucking, it also feels incredibly unnatural to perform a rest stroke. Half the time my finger comes into contact with my thumb, the rest of the time I have to tilt my hand more so that the finger goes towards the lower string rather than into the palm of my hand.
In addition, I cannot seem to perform a rest stroke without my nail coming into contact with the string. I pluck with the pads of my fingers, and have my nails as short as possible (no nail white left, although they still overhang my fingers), but the movement directly from one string to another causes the nail to contact the string I'm plucking after I release it.
My bass teacher used a pick and can't really help either sadly... Can anyone offer any tips or descriptions of how to perform a rest stroke in fine detail?
Thanks in advance for any help!
Dave
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