Ok so Stephen Hill wouldnt be chased because of injury concerns and would have minimal value. I suppose you can assume Steven's is being chased by Geelong which might increase his value a little bit to your valuation of pick 20-25 but I dont think too many Geelong fans would be happy with that unless he gets on the park at some point in the rest of the season and shows he can play still.
That makes 26 not too far off in value for Steven's anyway (per your assessment)
So your real problem is in paying 5 for Hill. If you want an elite contracted player, you will have to pay - see all our trades of late.
I think you've said yourself Hill is worth 10ish contracted. I'd say he's worth 10ish uncontracted, and he's contracted for 2 years.
As Shadow89 said, some other picks swaps might be needed but it seems to be pretty spot on all round
Upon further inspection and in a perfect world, I would probably change the 2nd we give up to a third, because Kelly is worth far more than Hill and a 10 pick downgrade. That's really just semantics though, as Hill is contracted, so it does up the value a bit.