Aren't you using the boiler to heat hot water? (If not, you probably should, but that's another topic.)
I wouldn't sweat the location relative to the AC compressor- even if condensing exhaust condensate managed to finde it's way onto the AC unit, the dilution factor of rain & snow would pretty much render it neutral, now that the acid-rain issues from power generation have been taken care of. Vent terminals for direct venting have to work in 50mph gales anyway, and there's no way the turbulence on the side-stream of the AC fan would approach anything like what you'd get out of a mid-winter nor'easter or a passing tropical storm. It's a forced-draft system, it takes a HUGE amount of wind turbulence to mess it up.
As far as clearances, in Canada to meet code you'd need to be 36" away from any operable window or door, but in the US a mere 12" cuts it unless specified differently by local code. If you're more than 36" away from the wall it would cut it even in Canada. Local codes (or the manufacturer) may have restrictions on distances to interior or exterior corners, but there's nothing enshrined in national codes on that, though parking it at an interior corner near a window could have some build-up issues at 12". There's nothing (other than glue, perhaps?
)to prevent you from rotating/angling the vent away from the house to guarantee that it's blowing away from the window.
Most manufacturers want to see the combustion-air intake on the same wall as the exhaust to avoid wind-driven pressure imbalances from interfering with it's operation during those 50 mph gales, and will specify min & max clearances. If that's
not a coaxial intake/exhaust vent, but exhaust only, where's the intake, and does that meet the manufacture's instructions?