I think you are pushing the top end of your truck’s capacity, especially for a longish TT. You might want to read many of the posts in the Towing section. Based on rear axle ratings and payload, many 1/2 ton owners are recommending somewhere around 6,000-6,500 lbs gross with plenty of margin, and it seems most of those are 24-25 ft boxes. It may theoretically work but the experience may be white knuckle and you could be moving up to 3/4 ton shortly.
2000 Coleman Tacoma Pop-Up
2006 Ford Explorer XLT, 4.0L-V6, 4x2