Idea 1:
Just An 8 Wheeled Shunter Loco But Not In The Typical Fashion
Not 2 Bogeys With 4 Wheels Each, Just One Solid Bogey / Frame With Everything Else Above It (possible dh or de)
Maybe Something Like The Sentinel 10143 Or Others Like It
Idea 2:
Just Simply An Extra Fuel Tender, A Small One And A Large One That Can Fill With Water Or Diesel And Then Hitched Too A Steam Or Diesel Locomotive (but this would have an mu cable on it to transfer mu control thru the tender also yes, plz make an auxillery water tender that can attach to the 060 plz)