Using a van to tow a boat should be fine as long as you stay within specs. Also, having a weight distribution hitch like blue ox towing or sway control bars makes a difference.
Hi
Definitely the van...if it's FWD.
the Lexus IS surely rear wheel drive ? Not great on a less than adequate slipway or a greasy tidal slipway with drive wheels in the water.
I had a similar dilemma recently....
I stupidly sold my Discovery 3 (best car I've ever had...after the usual problems were sorted out) and bought a RR evoque. Didn't take me long to realise this would be a rubbish tow car. I also have a BMW 530d GT....so the choice was putting a towbar on the RR or the BMW...you may be surprised to hear that I opted for the BMW.
It was a hard choice, but I figured that I won't be keeping the RR for long (because it's that bad) and I would the BMW.
The BMW is great at towing on the open road and does it effortlessly. However, my boatyard has a wooden slipway and it's not easy to pull it out with the BMW. The rear wheels are in the water and the slipway is like an ice rink.
Technique is to put it in Manual sport mode with traction off and put it in 2nd gear. A bit of rocking back and forward is required at first and feathering throttle and managing wheel spin.
Needles to say...I miss my old disco 3 !