What system should I use ffor a gig in a tent?

Allo guys,looking for suggestions about a sound system that will be neened in a gig comin up! I just learned that this gig that was suppose to be inside a building will be in a tent,,well for about 200 persons,so I just played in similar condition three weeks ago,and without being miked,it was desastress,and really bad experience!
Playing in a tent ,is like blowing a sax with a towel inside,no projection,no accoustic at all! There will be at least 200 persons inside that cocktail time,so even worst, the accoustic will be dead as can be!I want to rent a system so at least I wont kill myself blowing,and also will have a naturel sound,with at least a good natural sound result!
Any suggestion,what kind of system,mostly what speakers size would I need,,,not to be annoying,but at least to have a presence and good qualitee sound!My microphone is a simple Sure Beta 57,which is find!
This will be only as a duet,piano and saxe!The piano has a an amplifier!
Thanks for your comments!
All the best
Saxobari