I’ve never had any heat issues with insulin and my pump has been trekking in a rainforest, on safari in Africa and sailing in the Med so it’s spent plenty of time outside of the typical British summer. That said, I don’t really want to add skin cancer to my list of woes so I don’t tend to spend much time sitting in the blazing sun for hours on end.
I use 30cm tubing and that’s long enough for me to wear my infusion set in my thigh, stomach, bum or back and have my pump clipped to my waistband, keep it in my pocket or clip it to my bra at the front if I’m wearing a dress. If you’re looking for pump issues, my biggest one is where to put it when wearing a dress – you can get garter type things that go round your leg or torso but I don’t like them. I’m assuming the dress side of things won’t be a problem for you Mike? 
Pumping isn’t the perfect answer and it certainly doesn’t stop diabetes being an inconvenience at times but for me it’s just a much better tool for the job than MDI.