You must like your tomatoes, I've only planted 5 this year and one cucumber plant.
Last year I had a massive yield from a tomato I was told about by some of the old-timers down the allotment.
The tomato plant is called Shirley F1's, I got that many last years of two plants I was sharing with my mum and my neighbors.
I use canes to hold mine up and like you said the weight has been an issue for me too.