I'm also towing a 13 footer Boler
with a 2007 V6 Rav4. I started with a 2005 4-cyclinder, but it just didn't have the power on the hills or the control coming down. It was not heavy enough to carry the weight
of the trailer. Downright scary coming down the pass. It also felt it was a bit bouncy at 60 mph.
The Rav4 v6 is very balanced and stable. 60-65 mph on the freeway is no problem, nor is going up or coming down the Cascades. I don't have a sway bar or brake controller. I keep the trailer as light
as possible, and load gear in the Rav4. Another great thing about the Rav4 is the cavernous back area. With the seats down, I transported a 6 foot tall Rubbermaid storage unit. Lumber and hay bales are no problem!
I turned the ball up so it is level with the trailer. No drag.
Yes, the side open door only opens to the hitch when hooked up, but that's ok because if I want to load things like a kayak on top, I can stand on the back bumper. I could not do that if the door opened up. And given the height of the Rav4, I'd be pushing around a stool for height.
The only sad thing about the Rav4 is that the 2014 and new models do not include a V6. So some of us (me) will be sucking every last mile out of it before deciding what to get next. Luckily that is about 5-10 years away for me.
Good luck with your decision!