Potatoes and onions have really long shelf life and can last for months if kept in cool, dry and dark places. However you should not store them together as potatoes go bad really fast if stored near high ethylene producing food like onion, and onions get leaky quite fast from the humidity they absorb(?) from potatoes. Let them breath, and don’t keep them in locked containers, I usually just hang them with mesh bags

For carrots, bell peppers and cucumbers, I usually add little bit of water into a sealed container and it is enough to last another 3-4 weeks in the fridge

Pickling is also an option for all of them if you like it

Frozen cucumbers and bell peppers won’t have a great texture, but it’s fine for me to chuck them into soups, pourées, etc