iKey® partners with Gamber-Johnson often for forklift mounting projects.  Here are a few solutions to look at from Gamber-Johnson.  You can find more information at their website, www.gamberjohnson.com

Helpful Links:

Forklift Low Profile Tablet Keyboard Bracket: # 7160-0984 http://www.gamberjohnson.com/products/forklift-low-profile-tablet-keyboard-bracket

Other keyboard brackets for forklifts, whether you want to mount horizontally or vertically, they have a solution: http://www.gamberjohnson.com/material-handling/forklift-mounts#product-type-1022=289

The above link also shows the mounting solutions for an iKey numeric pad, Zebra tablet and quick release keyboard tray assembly.