I put 37 in their patch. 3 rows, 20ft long each. It was originally supposed to be 27, however, the maternal unit insisted on purchasing 10 hybrids at the nursery which we found a way to fit in, so, spacing ranges 18-22" between the tomatoes in each row. It sounds close, but they'll be trained to a single vine on a lower-lean system
At home, last year I had 13 tomatoes in diy SWC/SIP containers using grocery store shortening and egg buckets. The SWC did not work, because my mix was WAY too lose, I had to water 2-3 times everyday. I threw out the containers, they ended up breaking end of the season. Soil was repurposed for winter crops.
This year, I had planed to do only six dwarf tomatoes, however, I have a total of 15 since I can't get rid of the duplicates - had a lot of trouble with the seeds germinating and then all of a sudden I had double what was intended. Ugh. The containers will be a mixture of 5 gallon buckets and grow bags, the medium will have more peat moss / coir this time so I don't have to water as much! Three of the buckets have a SIP-style doohickey I plug into it, but, I can do the PVC thing for the remaining buckets (but not grow bags, I suspect that would leak out) if I don't end up doing double-bucket SWC. All TBD. I also found stuff for "Earthtainers", which I wish I had time to build right now, that looks like a very promising way to do container tomatoes!