I expect that Rene Herse 42 or 48 or 52 mm tires will give you low rolling resistance, lighter weight, and plenty of cushioning -- even my 28 mm extra light Rene Herse Elk Passes at 55/60 f/r are surprisingly smooth over small bumps, and the 42 mm Naches Passes ELs ditto at 40/45 psi,
Back to multiple wheels: IME, a pound or 2 or 3 really makes little difference to the feeling of speed, even uphill. Some of my fastest "feeling" bikes were rather heavy, and with rather heavy wheels. Tire quality makes more difference than wheel weight, IME.
Also, bike setup and position makes a bigger difference in ease of pedaling than a few lbs of weight, particularly saddle position with respect to crank, IOW, torso angle at hips, which depends on proper saddle setback. A saddle too far forward, or a hip angle too small, can make your pedaling "weak" and awkward -- ie, you can't produce torque and it feels unnatural; I learned this 27 years ago from Grant -- long story often repeated. Moreover, a too-far-forward saddle will put more of your torso's weight on your shoulders, arms, and hands, and make your neck uncomfortable too,
As for multiple wheels: the idea is not at all strange. I use to have bikes with 2 and even 3 wheelsets. For a while I would have one "main" bike with 3 wheelsets (plus a beater or two): offroad knobbies with wide range gearing, 38 mm road tires for commuting with close ratio road gearing, and "gofast" with 200 gram skinnies and very close ratio gearing. More recently my Fargo had a 700C X 60 mm wheelset and a 700C X 35 mm wheelset, with disc rotors adjusted so that I could just slide each wheel into place without fiddling with caliper adjustment, And my 1999 Riv Road custom gofast will, God willing (hubs and rims with builder), shortly have 3 rear wheels, the "main" one with a flip/flop 15/17 t fixed hub, one for longer rides in rolling or windy conditions with a medium ratio 2-speed internal gear Sturmey Archer fixed hub, and one for steeper hills with a wide ratio 2-speed internal gear Sturmey Archer fixed hub.