This is a 10 year old small truck with a short wheelbase and a 119 hp 4
cylinder engine. Both the base model SX and the fancier SE have an
original maximum tow rating of 2200 lbs, and the SE "cab plus" had an
original tow rating of only 1380 lbs.

With this old a vehicle, I would recommend towing no more than 75% of
the original tow rating = 1650 pounds (for the SE & SX regular cab).
That weight would include all gear you put in the camper, plus the full
propane tank, A/C, awning, etc., which may not be included in the
'sticker' weight of a camper.  This would be only if you also limited
what weight you carried within, and in the bed of, the truck itself.
The camper would require brakes as well (and a controller for the
truck).  I don't care as much if you burn out your engine or
transmission, but I sure want you to be able to stop if I am driving nearby!

There are practically no 20 ft campers even remotely this light,
especially more recently manufactured ones.

Bottom line, with this small vehicle, I would not think it safe to tow
more than your mother-in-law on a rope!!