Umm...I run SimCity 2000 on a Voodoo screen here without much problems.
It was a bit tricky, but here's how you need to do it:
Use ModePro or NewMode, choose a 640x480 screenmode (other resolutions won't work), and check off the "Force Planar" option.
I don't know anything about a-train, but you should take a look at
GFX-Base for a good list of AGA/ECS games that are mode promotable.
Also a last ditch option would be to get a TV-Card and use the A1200's composite out (or use an A520 for a big box Amiga) to pipe it into the TV-Card. You can then play your AGA/ECS games on a fullscreen using a utility like Tickly's SuperTV for Mediator systems.