Wheel diameter, is it 700c?
On my road bike I can quickly attach SKS Raceblade Pro XL fenders for my 28mm tires. I do not think tires much wider would fit. They are designed to be attached with quick release elastics, but you can permanently attach with zip ties according to the instructions. They are not "full" fenders, but do an 80 percent job instead.
Rack capacity in weight? Do you need to carry more than you can on a rack that clamps to the seatpost? Similar capacity instead could be had with a big Carradice saddle bag as a different option.
I have a smaller Pendle Carradice saddlebag and handlebar bag on my road bike in the photo, plus the Raceblade fenders. My Carradice is hanging from a shimmed long 17 degree stem and DIY support I made from aluminum rod, not an off the shelf product you can buy. Frame size is 58 or 59 cm, a shorter frame size might not work with my DIY support.
Closeup of the rear fender:
If you needed a compact rear rack, Racktime makes two versions of the Foldit rack that can be disassembled for more compact travel. But that is a lot more assembly and disassembly than you might want for frequent train rides.