I don't think 2 businesses can use the same equipment or vehicles otherwise it can be classed as Tax avoidance! Having a 3rd company that leases the equipment out may be possible but I'm not an accountant .
There was a window cleaner on YouTube, I can't think of his name now. I'm sure that's what he was advising. I thought at the time people pay very intelligent people thousands of pounds to find loopholes. So it couldn't be that easy