The biggest I've towed with my L Series was 300 concrete slabs which (calculating afterwards) is about 2,000kg, plus trailer and in a horrendous blizard! The trailer was a commercial one rated to 750kg and it popped a wheel of the hub! TBH, it struggled with that weight, partly due to the actual weight, partly weather conditions and partly due to the tyres squashing flat! My Bad! I learnt a fair bit that day about towing.
The next biggest thing I've towed is a Series 3 109 SSW which is about 1,600kg plus transporter trailer that was up to the job. The Freelander coped quite well, but I wouldn't want to do major journeys with that load.