Why not just shrink all the squads by 1? There's no "need 10 to get the special weapon" requirement like Marines. Granted some are at the minimum already, but 1 Reaper plus 1 Warp Spider plus Avenger plus 1 Wraithguard plus 1 Banshee should get you close.

Maybe change the Reaper Exarch over to a EML to get another S8?