As a postscript to my own question should someone be looking at similar later, in practice the sensors were found to work perfectly well at 3v3.
Described as 5v working, 0.5-4.5v signal range, the effect is pro-rata at 3v3 in terms of voltage but the ADC output is identical for VCC scaling - viz, ZERO pressure is 10% of 1024 the range is 80%