Answer: To be honest, in my personal experience both of those critters are a problem to control and the most effective solution over time is a fence, although some gardeners do report success using home remedies such as pepper spray and commercially produced repellent sprays.
Removing the growth tips will limit the height of the vines, and of course smaller vines will produce less fruit. (If you had determinate plants and they had reached full blossom set, then there would be a serious problem.) Indeterminate plants will overcome the tipping much better, however. With ample water and fertility and cooperative weather you may still be able to enjoy lots of tomatoes.
Tomato yield is dependent on blossom set and then on general growing conditions. They do best in a rich, moist yet well drained (meaning not soggy) soil, well enriched with organic matter and they need full sun. Make sure your plants are well fertilized but avoid an excess of nitrogen, then be sure they are well watered, receiving between an inch to two inches a week. A layer of organic mulch will help, too.
Good luck with your plants!
Q&A Library Searching Tips