Can't say I've ever done a mod like that but wouldn't blame anyone who did. Webers overall are kind of low, which I presume is a stability thing on the tubular legs?
If / when I get a new 22.5" I think I'll get a sexy blue OTG kettle and build a kamado-style table for it at a comfortable height for prep and cooking.
Are you thinking to mod the cart itself or just build a platform the whole unit could sit on to lift it 5 or 6 inches?
~ Scott ~
Blue Weber Performer + Craycort CI • Brick Red Weber One-Touch Platinum • Weber 26.75 Kettle • Akorn Kamado • ET 732 • Record-crushing ORANGE Thermapen • UDS In Progress