I think the tweak of the spa is the best of both worlds! Well done!
Looking the the pic of the property I do have one concern I hope someone has already addressed. See the driveway over the ditch? That is going to have to be reinforced to get the big equipment over it without breaking it. I would try to find a way for them to come and go without using your driveway if at all possible. Of course that area will have to be redone when it is all over.
When it comes to future proofing the outdoor space for future utilities such as for electrical, gas, water input, water drainage, low voltage, A/V (HDMI, speaker, ethernet, etc), what is the best approach? Is it simply running as many conduits as possible? Any help centered around this is much appreciated!