Maybe medium format is the best idea. To go from 4x5 back to 35mm must be like going from watching a movie at the IMAX to your mobile phone. The are medium format cameras out there with tilt/shift if you need it, and the difference in technical resolution/image quality won't be so much of a shock.

If tilts/shifts don't matter to you so much, there are cameras like Mamiya 7, handles like a 35mm, gives resolution more like 4x5.