The root cause of the clearances was the need by Clan landowners to derive greater income from their lands - combine this with an increasing population in the highlands and a collapse in kelp prices after 1815, then you've got a situation where the clearances really are the only logical thing to do (from a purely economic point of view, of course). I'm not entirely sure how you could have avoided those pressures coming into play: the obvious example would be making a success of the Darien scheme (not technically post-1700 but close enough perhaps?) or some other imperial scheme in Africa or Asia, which would - at least theoretically - give investment opportunities to Scottish landowners outside of the exploitation of their domestic estates. (Of course, that then opens up all sorts of issues regarding what this new colony looks like, what its relationship with Spain is and so forth.)