Finally! I have 3 such fans, one needs a motor but mechanically all are fine. Wanted to build these enclosures a long time. Until now, had puzzled on what to use for screening. Never thought [unaware] of agricultural material, other fencing varieties are flexible. Saved me some RPM testing too, will copy 172.5 recommendation.
Do your large fans 'walk' out of position? 3 wheels [1 crazy, 2 straight] is correct, too many uneven surfaces, 4 usually unstable. Kick-out casters would work too, for parking.