I'm assuming you've grown them in these same high tunnels with a very different growth pattern.
So the plants look healthy but are growing without much fruit but a lot of vine. I'm also assuming they're not leggy but rather just have a lot of foleage. I think you're right in diagnosing it as too much nitrogen.
http://homeguides.sfgate.com/signs-m...oes-72800.html
They're saying you can add bonemeal or colloidal phosphate to fix the problem.
If they're too tall you can also top them. One time I was fruiting a tomato plant indoors and I think I accidentally cut off the lead growth. Instead of kicking off more suckers it just kept kicking off fruit sites. I had 2 fruit sites at every node. 10" tall plant with > 50 flowers. What I'm saying is that I think you can still get good yield if you can get the soil balanced even if you cut off the terminal growth.
I've grown most of my plants indoors so I don't know much about pests.