According to the Bailey web site the 2009 Senator Louisiana's MTPLM is 1686Kg.
The current Galaxy data from Ford indicates that you would need a minimum of the Diesel 2.0litre (140ps) engine. Which has a max permitted towed limit of 1750Kg, with a kb of 1805 to 1840Kg (depending on exactly which model) This would give you a ratios of about 90 to 95%.
Weight ratios are not the only thing that affects towing stability, you must ensure good load distribution within the caravan, and most of all don't expect sports car handling when towing.
In its favour, the Galaxay (and other mpv's) have relatively long wheel bases, and relatively short rear overhangs, and this is usually a positive advantage when towing
These models would be compatible in terms of legal weigh limits. But as always it is better to keep the trailer as light as possible - (move a few more items into the car.)
Compared to the Disco, the fuel consumption should be much better.