Daintree,
I grow yams up my trees as well.  They are an easy to grow great food source. 
You can mound them to give them extra space to grow.  I also have used bamboo poles and lean them against the tree to form a teepee trellis.  This allows you to plant the yams further away from the main trunk for easier harvest.  It can also make a nice living shelter for kids to play in if you do this around the whole tree leaving an opening.  Hope this helps some. 

Wow, that’s huge, 111 Hawaii’s, the only meaningful comparison 😁🤙

With that much area you can always find the right latitude, elevation and humidity. Guessing rainfall or irrigation is the biggest limiter.

Probably getting off topic here but pictures I see of Aussie lychee groves are often hedgerows. With abundant land for generous tree spacing I have to assume this is for easier netting? Still, the labor cost of pruning must be expensive. Came across this when researching EL origins:

In addition, he tripled his yields early on by gradually increasing tree density from the standard spacing of 10 metres by 10 metres to a more intensive six metres by two metres.

This planting design was unheard of at the time but Tibby said the rewards were clear.

“There is a bit more pruning but it’s safer – you don’t need ladders, it’s easier to pick, it’s easy to spray, it’s easy to net. You’ve got five times the amount of trees in that row,” he said.

“End of story you get more money in your back pocket.”

Crazy! 6 x 2 meters spacing for lychee fruit production?! Labor must be very affordable to make this work.

https://www.growcom.com.au/portfolio/rainbow-orchard/

I almost regret buying my Sugar Loaf after reading this thread, almost.

Have yet to try a sugarloaf, but based upon the growth pattern on both sugarloaf and m4 in my yard, sugarloaf is a much prettier tree with nicer growth habit. Short nodes and lots of flowering sites.

m4 tree is looking good, and is a wonderful fruit.

glad I have both, and coco cream

there's an "improved" isan indigo floating around

Mike (achetadomestica) in FL had some for sale earlier this year at an excellent price... I bought some and I had 100% germination from them within 2 weeks.
I also bought some from a forum member in HI that germinated well.
Now I wouldn't go throwing around the phrase "Ripoff" so easily....
They advertised a product... at a price... and it's up to you as the educated consumer to decide to buy or not.
I'm sure they feel their price reflects the quality of what they are selling... I would not assume any nefarious intent.
From time to time... I go through periodic obsessions with certain plants... and I find myself plunking down top money for
the seeds or plants etc.... just part of the game!

Kevin