YES, dragging so long puts you off hydrofoiling - we have one spot with same conditions, and we have all tried this spot once (sand so no risk), but it is a real turnoff and we all seek other spots and never return to this otherwise best TT spot with a good social atmosphere.
So if this is your local spot, get a 60 cm mast - you will love being able to foil all over and start much closer to shore.
There are hardly any waves I assume, when the depth is so low, so no problem riding with shorter masts IMO and experience, eventhough I personally would prefer longer ones but I have the luxury being able to choose between literally hundreds of different spots in the vicinity.
In real low onshore winds a 60 cm mast is in fact the ONLY way one can hydrofoil, so you will like having a short mast even if you move to another spot
Go for it