My understanding is that the draw-tite hitch sold by U-Haul and IPD is the better of the non-Volvo OEM units...I loved my Volvo OEM I had on my '79. Doing the trailer lights SHOULD include a cool little box to avoid tripping the bulb out relay every time you push the brake pedal

As far as how much you can tow depends on what, and where, you are doing. With two on board, small enclosed trailer, and mix of urban and highway...stick to a max weight of 1500#'s for trailer including its cargo. If the trailer has surge brakes I am comfortable up to about 2500#'s. Flatbed I am comfortable going up to the max of 3300# if the load is relatively low profile.

Keep in mid all the normal trailering issues like crosswinds, increase braking distance, etc. Also keep in mind that Volvo has a very low tongue weight max (200-250#'s) so the quality of your loading a trailer is very important.