I've been using a Wilson Sleek 4G-V for a long time, and the indoor cradle and outdoor antenna are only 4 feet part. However, my TT has aluminum roof and siding, which should block the antennas line of sight.
I tossed the laughable tiny rubber duck antenna and installed a Wilson high gain marine antenna, it's a nice fiberglass unit and has held up very well over the years.
IMHO brand of booster isn't going to affect the need for antenna separation - that's physics. Any unit that claims you can use the two antennas close to each other is just pulling your chain.
