I don't know about cukes and sweet peas together... when I grow (snap) peas, it is as a cool season crop... would the summer weather be too warm for sweet peas?
For what it's worth, in the past I have grown either asparagus beans or else regular pole beans on the same trellis as my cucumbers, so peas should be doable. (Beans and peas are both considered to be companion plants for cucumbers.) However, the beans tend to be hidden by the cucumber vines, so you have to hunt for them. (I imagine it would be the same for peas.) You also have to be on the lookout for pests that one plant might attract, that the other usually doesn't. (For whatever reason my asparagus beans end up being swarmed by aphids; the cucumbers, not so much.)