I've got a 1.9m motorize dish feeding a skystar-HD2, with a BSC-621 dual band LNB (5150,10750) I
#1 limitation is the dish size. Too small of a dish will see too much of the sky at once for CBAND, resulting in adjacent satellite interference that nothing you do can ever overcome.
#2 limitation would be the BSC style lnbf.
I am sure you could get one of those to work OK on a large antenna, like say 10 to 12 feet. But no way on a small antenna. I would take what I could get for now and not kill myself putting all sorts of money in to. Use it to get used to using a satellite system in general. Meanwhile keep your eyes peeled for a larger antenna and save your money to beef that up should something become available to you. If I had my way, I would put up the 10 ft fiberglass I have, but some battles are just better off not being fought
I wouldn't go less than 8ft for CBAND around here.
You could also keep the 1.9M for Ku service (should be fine for Ku) and dedicate a future large antenna for CBAND.
I would expect to have less trouble with some of the stronger DVB-S signals, than the DVB-S2 signals.
For DVB-S2 signals everything needs to be "Spot on"
So, back to your original question... You should be able to get signals on both polarizations though, provided the signal is good enough on the transponders your
looking for. For 103W, you confirmed the PBS mux on Vertical, that's a DVB-S QPSK signal not very hard to pick up. Try the ION mux at 3840 H 26680.
It is also DVB-S QPSK and should be just as easy to find.