You can always get a feel for soloing even if you have a full party by sending in one character to try and clear out an area - actually sometimes it's
easier to clear out some areas with one character than with a party (sometimes too many people get in the way) - of course you might want to wait until your XP is fairly up there...
For instance, Edwin (having the Staff of Magi helps) clears out a whole nest of beholders by himself without a rest [and even without using the polymorph-to-mustard-jelly-and-zapping-with-cloudkill-wand trick either]
I'd recommend reading "The Journal of Elmonster" from Baldurdash.org as the mage goes into great detail (while roleplaying) of his tactics. (
http://www.baldurdash.org/journal.html) A nice read, as well as informative.
And I just finished MY first SoA solo with a Blade and she rocked quite easily especially after level 15 or so.