But one can *section* the design so that each section carries a portion of the total current. Current mode control readily lends itself to this practice. Using 8 to 10 sections makes the design quite feasible.
At low battery, however, it depends on whether or not a full 2.0 amps is needed. If a reduction in max output current can be tolerated, maybe it can't be as I don't know the function, then it gets even easier. At 12.0V input, with 85V/2.0A output, the power is 170W, which when divided by an efficiency of 0.90 gives 188.9W. At 12V in, this gives 15.74A average current at the input, but the average inductor current is 123.9 amp, quite a lot. With 8 sections, it is 15.5 amp per section.
Not easy, but feasible.