Can I power multiple Constant Current LED fixtures with a Single Constant Voltage Driver?
If you dial down the voltage to 50 V then monitor the current rise with temperature as Vf reduces -0.1%/‘C or ~-0.5V then you should be able to adjust the current and temperature so that they do not overheat with a 700W supply to have margin, as it is a bad idea to load a supply to &gt;=100% for reliability reasons.
You might then be able to Make a dimmer with a Nch Fet rated for 10x the current or a really good heat sink.
Use a a smallish power shunt switch resistor to have a minimum load current of 5% max.  if the supply is unhappy then add an LC LPF with a 2 Ohm impedance at the switching rate for good dampening.
You may adjust my estimates.