Is there anyway you can set the charcoal basket higher? I have the option on my UDS to place a grate right above the charcoal basket for a diffuser or water pan. Also serves the purpose of elevating the basket to just bellow the cooking grates so I can hit grilling temps. That would certainly work for your situation if that option is available to you.
18.5" OTS, 22.5" OTG, CB Silver(Rip), Vintage Coleman Bullet, Pit Barrel, UDS