5 string strings and tuning

I'm new to dulcimers and have one that needs the strings replaced.  I did a bunch of research of the various types of tuning, strings, etc. and came across a string gauge calculator.  On of the things I've noticed is that it is difficult to find a set of strings for a 5 string, so I've decided to go off the reservation a little and build my own set of strings.  I've decided to try to set it up similar to a 12 string guitar in sets of octaves using D'DAdd' and the following gauges of strings (from low to high) .033", .019", .012", .009", and .008".  I figure, worst cast is that D' and d' may give me some problems tuning that low and high respectively, in which case, my back up plan is to tune those strings to  D and d to match the set they are in.

I don't know if anyone has insight into whether this is do able, but I figure, I'm learning and I'm bound to make a few mistakes.  

Comments and insights are most welcome.