Here's alternative idea.
Set the lowest pin to, or just short of furthest distance you think you may be shooting, then set the highest to around 20 metres. Now evenly space the remaining pins between the two set ones. Go out and shoot using these pins to find out what they are set to. You can either leave them as they are, or you might like to move them slightly so that they are on easier to remember distance, e.g. if one gives, say 43 metres, you could move it to either 40 or 45 metres.
For shorter than 20 metres to where your sight marks change direction, you would put your top pin just below the target.