I only can comment on towing a small Gypsey (GVM 750kg) with my 3,2 D-ID SWB.
I did not even feel I was towing something !!! BUT WAS SEVERELY LIMITED IN LUGGAGE SPACE !
I now have a 3.2 Diesel LWB and tow a Conqueror Supra 1 with a GVM of 1.500kg and I know that I am towing it, in particularly uphill or during overtaking
The GVM difference between SWB and LWB is approx. 400kg (Tare maybe 200kg?). Dont forget the LWB is +/- 500 mm longer, carries 2 additional seats , has a larger Diesel tank ( 20 l more )and therefore is also heavier
400kg loaded or not in addition to a caravan will have an effect
The much better departure angle of the SWB is of no advantage to you if you are towing a road caravan but it might help if you tow a 4×4 or off road camping trailer with a high ground clearance.