Aluminum lightweight car trailers are readily available. However, they cost an estimated 6 to 8 thousand dollars. It just might be better to get a vehicle that can be towed four down, such as a manual transmission Subaru or possibly a Jeep Wrangler (I recommend the Jeep, 2003 to 2006. I don't like the new ones.)
They are right: you can't tow an all wheel drive vehicle on a dolly. Only way you can tow such a vehicle is all four wheels on a trailer. As @mowermech suggests, your best bet is probably another vehicle. Some Jeeps were offered with a transfer case that has both AWD and traditional 4WD as well as (most importantly) a neutral specifically for towing 4-down.