‘Locational’ Instrumental with Prepositions

I was making up a bunch of words tonight and also some example sentences to go along with them and came across something like this:

[gloss]Ang pukay manga eyrarya lahanya.
AT jump-1SG.TOP MOT over fence-LOC[/gloss]
‘I jump over a fence.’

Now, I’ve long kind of disliked eyrarya ‘over, above’ as a word itself and should maybe replace it with a word I like better sometime.[1. The issue I take with it is that it’s a rather basic lexical item but it’s derived from eyra ‘below, under’ with the negative suffix -arya, so basically ‘un-under’, which I personally find very confusing and which has led me to confusion in the past, in fact.] However, in relation to an earlier blog entry, “‘Locational’ Dative and Genitive with Prepositions” (Apr 2, 2013), I was thinking about why not making use of a device I came up with to express lative (moving to) and ablative (moving from) motion and extending it to perlative motion (moving through, across, along) with the instrumental, since that also already covers the meaning “by means of”. So another possible way to express the above may well be:

[gloss]{​Ang pukay} (manga) luga lahaneri.
… (MOT) top fence-INS[/gloss]
‘I jump over a fence.’

The motion particle manga may not even be necessary since ‘by means of the top’ in conjunction with the dynamic action ‘jump’ in my opinion already reasonably conveys that the person jumping won’t get stuck straddling the fence. Besides, ‘jump onto’ would normally be expressed like this, since the simple locative conveys a static meaning, i.e. one of resting in a place:

[gloss]{​Ang pukay} manga luga savaya.
… MOT top wagon-LOC[/gloss]
‘I jump onto a wagon.’

Whatever eyrarya may end up as in the future, just describing something resting over a thing would still use that word to make clear that the thing is not sitting on top of something but hovering over it. Alternatively, there would be an opportunity here to get rid of dedicated words for ‘over’ and ‘under’ completely (at least in transitive contexts) and just have them be ling ‘top’ and avan ‘bottom’ plus instrumental, and manga would after all indicate that motion along that point is involved.