1 1/8" forks in a 1" headttube, have a look at my IS41 adaptor and let me know what you think!

ive never been sure about this heating up or cooling of press fit parts. if you heat a doughnut shaped thing, doesn't the ID shrink and OD expand?

doesn't the ID shrink and OD expand?

Nope, both ID and OD expand. Imagine the atoms next to each other forming the innermost layer of the ring. If the distance between each two atoms goes up due to heat, the ID naturally increases, too.

this will be done by rule of thumb. Do you think it's feasible

You want your load to be approximately what it would be in a normal build. The standard load is the expansion of the head tube by most of the interference value over the length of the cup skirt. You will be substituting a shorter ring made from much less stiff material, and you can't increase the interference because you'd be getting too near the elastic limit of your cup, so all to have left is making the radial thickness bigger. Obviously the steel tube starts with a pretty thin wall, so you're already ahead without even trying, but if your engagement length is cut to a quarter of the usual value and your tensile modulus to about a third, you want to be of the order of 10 times the radial thickness to compensate.