In general trying to create a vacuum airship is a loosing game because you have to add so much support to prevent it from collapsing that you can't win the race

In general trying to create a vacuum airship is a loosing game because you have to add so much support to prevent it from collapsing that you can't win the race between volume and weight to achieve buoyancy. The thinner atmosphere is a bonus to decreasing the force for a given volume but you simultaneously have to increase the size of the 'balloon' since it's displacing less air for every unit of volume so it has to get bigger which increases the surface area further. Doing some quick math using the ideal shape of a sphere: Mars surface atmosphere is ~1/60th as dense as the Earth's so you'll wind up with 23x the surface area which at the reduced surface pressures of mars you'd be looking at around 15% of the total forces you'd have to resist. For a sphere that might just push it into the realm of possible options but to get to a 'pure' vacuum you need very fancy and heavy pumps that need cryogenic cooling beyond the difficulty of doing this with an actual blimp shape.