First, I really hope you enjoy your holiday
I live in Africa, on the east coast, southern hemisphere, so my summer is in Dec/Jan/Feb - and it gets into the high 30'sC with humidity in the high 90% range. I have the ocean on my doorstep, and a pool in my backyard. During the heat of the day, I stay indoors in aircon - the problem is, at night, it does not really cool down much and is still very humid (not sure about Aruba) - that is when the pool comes in very handy! You handled it well last year, so I am sure you will be ok if you pace yourself. The heat makes me very weak, dizzy and tired, and the numbness and neuropathic pain even worse...
However, I went to the UK on holiday in Feb and it was so cold - below 0C at night with day time highs of 3 or 4C - and I had a lot more energy than I am used to (my winters still have daytime highs in the mid 20'sC, so I have not been so cold in years) - but another problem became more pronounced - stiffness and muscle spasticity were much worse, could hardly bend my legs and this was very painful
So my point I guess is, different weather extremes have different effects on us - and we are all different. You know how you are in the heat, and seem very sensible in knowing what to do to make it more comfortable for yourself, so I am sure youwill have a great time.