thanks Mark, P&D do seem to have ladders and steps, I'll make an order shortly.
I had considered the truck swap option, and may yet go that route, I was just trying to not have to throw out reasonable side frames. This is for my garden layout, and I'm not so I'm not as hot on good details as I would be for the indoor stuff, and those Atlas parts as you say aren't that bad all things considered. Talking of the old Atlas line, the switcher that I own is powered by a carved up F9 mechanism (previous owner's work) which ran pretty well until the plating on the wheels failed (at which point I changed to NWSL ones) and it carried on nicely.