I think it would be easier to just limit greenhouse gas emissions on earth.
Your point works pretty well considering that Venus has a a dense atmosphere unlike Mars.
The same technology could be used to reduce gw on the earth:
1. an orbiting sunshade
2. putting something in the atmosphere that makes it more reflective, like sulfur dioxide
I wonder how big a sunshade would need to be to reduce temps by, say, one degree. A specific location could be shaded by putting the shade in geosynchronous orbit. To finance the sunshade, put a Starbucks or Coca-Cola logo on it.
A single giant megaproject sunshade is not feasible. But it is possible to make many smaller ones, each diminishing insolation by just a few fractions of a percent.
> I think it would be easier to just limit greenhouse gas emissions on earth.
Of course it would, but that's besides the point