Rear shock recommendations (self leveling)

[bfeng]

I am going to replace my rear shocks.

Car is a 2011 x5d with 3rd row and self-leveling.
I tow a 5000-6000lbs trailer 8-10 times a year.

Why? Lately when towing it seems like I’m getting a bit more up/down motion in the rear. Plus I’ve got 125k miles on the vehicle, which seems like a reasonable lifespan for an OE shock. Car passes the bounce test, but that is not a valid test with the self-leveling rear suspension, and while I’m huggably chubby, I don’t think I weigh enough to do a bounce test with the trailer hooked up.

As you guys know, the OE replacement runs about $340 a side (list is >$400 a side). That’s more than the alloy double adjustable race shocks on my old SR!! No way...

I’m seeking recommendations and feedback from anyone who has tried the Bilstein B4 or B6 or another aftermarket shock.