third vote for the tires option
I have 2.15 DTHs on one of my old bikes - nice ride
2.3 DTH is also available
I run 2.1 Continental studs in the winter. The tire is rated for max 65psi and the front usually receives the 50-55psi treatment while the back gets 60. They're studded and I don't like to run them too low (already enough drag with them). I've noticed the front tube stem shifts from perpendicular to the axle if the pressure is not at least 45psi.
There have been many fine suggestions in this thread (tip o' the hat to you) and I'll try and cobble something together which will do the job. I'd say a spring loaded one will be the choice to make.