I'm looking for some advice on which X5 is best for towing a trailer. Here's some background for reference:

• I have a 6x12 single axle v-nose that I use to haul 2 racing sportbikes plus generator, EZUPs, toolboxes, gear, etc.
• Estimating trailer to weigh 3,000 with all stuff in it and probably another 1,000 for people/coolers/etc. so let's focus the conversation at 4,000 added weight
• I previously had a 2006 X5 4.4 that did an OK job of towing it. It didn't like being in 6th gear but if I manually shifted it according to wind/hills it did the job

What I'm trying to decide now is do I need a V8 (4.8 or 5.0) or will a 3.5 get the job done. It looks like the towing capacity is around 6,000 or so for each but I'm curious to hear some actual results noted from members here. I know this isn't the IDEAL tow vehicle but I just don't want a Tahoe/Yukon to drive around the 90% of the time I don't have a trailer behind.


Thanks in advance for any opinions/experiences.