Your stuck with 20" wheels on the SC. I believe you will be stuck with them on the non-SC 2011-2012 also.
That said, if you get the 2" lift and put on the larger tires you can still get Load Range E off-road tires for 20's and I've heard good reviews about them aired down. Still not 18's but not bad.
We did a test drive of an LR4, RRS, and L322 back-to-back at the $tealership. I'm looking to trade in my solid-axles for IRS/IFS to help my wife's back.
on road, the L322 was the most composed and drove the best, hands down. Felt like my 540i. RRS next, then the LR4, which actually had quite a bit of body roll (compared to the others).
Off-road, the L322 cleaned the competition (and much better on my wife's back), the LR4 next (it was close, but you could notice the articulation advantage of the L322, even on the $tealer test strip, with mod support the LR4 could no-doubt equal or even surpass the L322). The RRS was the least performing off-road out of the bunch, it seemed to have less articulation and felt more like a "sports car" on the inside (low seat position, etc).
Now this is all relative, as Chris' build on this site has shown (and my inspiration to check out IFS/IRS Land Rovers), the RRS can be built into a pretty sweet and capable rig. I just preferred the L322, there is a reason it has a higher sticker. And go for the surround-camera system. Could come in handy on obstacle approaches.
In the end, we decided to keep our truck (bad trade in) and wait. We will probably pick up an L322 within 3 years, hoping depreciation helps us out a bit.
I'd steer clear of the M62 BMW engined beasts. I loved that engine in my 540i, but it was no over landing power plant. Watercooled alternators and crappy plastic radiators don't work in 4-Lo in 100 degree heat and/or fording rivers. I wouldn't risk it, even with the alleged articulation advantage.
Both the L322, LR4, and RRS should tow your classic. I'd get the IID tool to disable the "auto level" feature on the rear suspension so that you can use a weight-distribution hitch properly.
The engine has plenty of power but the frame and suspension is no 3/4-ton truck. You'll be pushing your tow-ratings which means play it safe regarding hitch setup/tongue weights and don't speed even though the engine will let you.