Old rx300/mcu15 owner here - a towing question! Lol

[Swamp]

Hey all. I'm here to find some info on my partners rx300/harrier. It's a 1mzfe awd model, 1997. I want to fit a towbar and tow a car trailer (supposedly 600-900kg but will aim for the lightest model) with my MR2 on it which is approx 1200kg. 

According to this post https://au.lexusownersclub.com/forums/topic/1440-another-towing-query/ max capacity is 1700kg. AA nz website towing weights is bs imo, totally arbitrary, I'll believe what manufacturers recommend. 

My question is, if I tow a combined approx 1800-1900kg which is 'slightly' over the max of 1700kg will this be doable and safe? 

My MR2 sits at my mums house 350+km away waiting to be fixed when I crashed it when I was younger haha and I would love if I could use my partners "truck" /camry to bring it home. My only other options would be to a) hire a ute/diesel suv which I've estimated to be in the ball park of $500, (200 to rent a day, 85 extra km charge, 100 approx gas + trailer hire) which is just expensive in time and money, or b) sell my daily ae101 corolla that im getting this week and use that + savings to get a high km sh***er diesel ute/v6 commy/barra if I'm lucky and then just sell that once I've towed. Or c twist a mates arm and borrow his ute lol.