5 days? I'd leave the sidecases at home. Socks, underwear, a few t-shirts and shorts, pair of shoes, towel, some toiletries. That will easily fit in the topcase.
What sort of activities do you have planned on your trip? Is it strictly riding, or are you doing any hiking or non-bike stuff, too?
'06 V-Strom 650 For Sale[/URL], light blue, Givi E36 sidecases, E52 topcase with Admore lights, Madstad, SW-Motech crashbars and skidplate