I don’t think that is the definition of far field. I would have taken far field to mean the mic was placed far enough back to capture the entire cab/speaker rather than be pointing at a specific spot on a specific driver. More than a few feet as opposed to a few inches or less for close mic’ed. It would only be reflection free if it is recorded in a large/open space with the mic on the ground. I used to measure home theater subwoofers this way. We would put the sub in the middle of an empty parking lot and lay a calibrated measurement mic on the ground 2 meters away. The sound would still reflect off the ground and back up, but since the mic was laying on the ground it would not pick up the reflections. Measured this way the subs had much less low frequency response but also much smoother curves than you would see in room. Most importantly for us though, the measurements were consistent for apples to apples comparisons and not dependent on the room, placement in the room and mic placement. I never even thought about doing this for guitar IR captures but it makes a lot of sense. The extra challenge is that we didn’t care about environmental noise above 120 hz but for guitar cabs you are going to want an extra quiet parking lot or a very large room.