Firstly, I am a newbie in this forum.
Hi, all taikos
I am a landscaper. Hope to help you to solve your headache. Think that you might have done some survey, so, i'm just some giving some ideas for you to consider.
You may consider artificial grass for your garden, no maintenance at all and  normally covered with 8 years warranty for UV discoloration and degradation, then u can save most of your maintenance cost ady. Next, choose the plants for your garden wisely. There have plenty of less maintenance plants in Malaysia, however, it depends on your house sunlight direction and ground condition. It can be designed as a less maintenance garden and think your wife will love to have it. Actually most of the plants used/designed by developer's project are mostly more or less the same, because they try to avoid headache also in future maintenance, so their consultant will design the lanscape based on the actual site condition.
Also, actually there are few brands of ready made glass fiber swimming pool/fish pond available in malaysia which provides 10 years warranty to cover leaking and its system. It has less problem compare with RC swimming pool or pond which tends to leak after years, because of concreting not done properly or waterproofing issues.
And, maintenance cost for your landscape area only (Estimate ard 2000sqft and not include pool/ponds) is nearly around RM800/month at my opinion. If you keen to know more, hope to discuss with you further for your garden design.   
Lastly, here is some photos which done by us and think it might give u some ideas for less maintenance landscape design
<a href='https://pictr.com/images/2019/08/02/5gxaGJ.md.jpg' target='_blank'>https://pictr.com/images/2019/08/02/5gxaGJ.md.jpg </a>
<a href='https://pictr.com/images/2019/08/02/5gxmDB.md.jpg' target='_blank'>https://pictr.com/images/2019/08/02/5gxmDB.md.jpg </a>
<a href='https://pictr.com/images/2019/08/02/5gxZBZ.md.jpg' target='_blank'>https://pictr.com/images/2019/08/02/5gxZBZ.md.jpg </a>
<a href='https://pictr.com/images/2019/08/02/5gxgCn.md.jpg' target='_blank'>https://pictr.com/images/2019/08/02/5gxgCn.md.jpg </a>
<a href='https://pictr.com/images/2019/08/02/5gxUbG.md.jpg' target='_blank'>https://pictr.com/images/2019/08/02/5gxUbG.md.jpg </a>
<a href='https://pictr.com/images/2019/08/02/5gxN6c.md.jpg' target='_blank'>https://pictr.com/images/2019/08/02/5gxN6c.md.jpg </a>