Peppers and tomatos are both full sun plants, particularly in the north which your zone 5 is. A pepper plant can be grown in a 1 gallon pot, though larger wouldn't hurt. Tomatos can be grown in 5 gallon pots for large varieties, though they will likely require daily watering and at least weekly fertilizing in such a sized pot even in zone 5. Larger would make life easier. Please don't put more than 1 plant per pot if the soil volume isn't at least 1 gallon per pepper or 5 gallons per tomatos (unless they are dwarf varieties). The end result will just be less performance from each and your harvestable yield will drop per plant, but may be around the same per container. Don't be afraid to 'waste' plants, particularly when they are free. As far as science knows, they don't have feelings and won't feel rejected ;) As emotional humans many of us find it easy to emphasize with plants, but it's just anthropomorphism.

Patio tomatoes in #2 containers have been going for about $10-12 around here. ... glad you're happy with your efforts. ;o) Al

I don't know about others, but I do not lump them all together. With "peppers" and tomatoes, you have got at least 10.000 varieties of each. Growing tomatoes and bell peppers in one setup and with one nutrient isn't the worst you can grow together, though. Bell- and hot peppers (generally speaking) are not unlike tomatoes, best grown with high Potassium and relatively low Nitrogen formulas. Well, tall bell pepper plants are often growing fast and can use more Nitrogen than their smaller relatives. And, most hot peppers (c. chinense, c. baccatum, frutescens and pubescens are much happier with lower nutrient concentration but don't mind somewhat more Nitrogen (in respect of lower concentration) as tomatoes. PH is compatible anyways, all in all - no big deal to grow them together, as long as you follow these rules that aren't a big secret anyway. ;-) Btw: your Cajun Tabascos should be capsicum frutescens, and in case, they grow slowly and build up quite a structure before going to blooming and fruiting stage (what you aim for in fact) - and hence they will take several month to mature and grow best with low nutrien concentration and high potassium content (as seen earlier). The good thing about them is that they are quite robust and forgiving, if treated decently... Btw: Capsicum frutescens is what grows best here in Thailand and in this "rough" climate.

Did you mean to as if your tomatoes will be hot because of the proximity of the peppers? If so, the answer is no. If you mean what you wrote, your peppers will be hot or not regardless of the proximity of the tomatoes.