I agree that the tree looks healthy and I would certainly get rid of the banana plants next to it. They spread and will be a problem in the future.

I have always bought 3 gallon plants if possible. I usually cut them back at planting and shape them as they grow out. They are easier to transport and plant and are easier on the wallet too.

Angie, cut down to 15 inches last year at planting

Mahachanok, cut down to 15-18 inches 5 years ago

There is plenty of ground clearance under the MC without the additional 2 feet of tree trunk. I have no disease problems either.

I drove to Orlando and brought the MC back in its pot. Also, Mickey's 3 gallon plants are noticeably larger than a 3 gallon elsewhere. He will (or used to) send you a picture of the plant. Contact him and ask questions. http://plantogram.com/contact-us-/

I thought I would try something new. I decided to start fertilizing my Maha. I started several weeks ago when I first saw the first signs of swelling hoping to halt the flowers and let it put out new growths instead. Coincidence or not they are now bursting with  new growths, no blooms that I can find. Almost every branch has 1-4 new shoots growing.

I did the early season fertilization with my new mangos for the same reason after they were planted in 2011. There were some flowers but mostly vegetative growth was produced. The trees were pruned at planting too.

Of interest to those of us that live in storm prone areas. Nothing is said about root strength.
http://phys.org/news/2016-02-trees-size-species.html
42 meters/sec = 93.95 miles/hour

I'm surprised they haven't used genetics from an existing citrus species, rather than making a transgenic organism.

One of the genes being tried is from a close citrus relative but that would still be transgenic. I don't remember which species it comes from. Another trial uses a gene from spinach.
Trying to kill two birds with one stone, these trees are being evaluated for canker resistance too. From what I've heard, this has also been achieved.

I just returned from a TBRFC meeting and the presentation was about promising new citrus varieties. Their HBL resistance is generally better than current citrus. Much recent research at UF has been on rootstock resistance and field trials are underway. Seeds for these resistant stocks are in short supply so it may be a while before plants are widely available. Even with this advance, in FL citrus will need some special care (fertilizing) to do well. Citrus is no longer 'plant and forget' like it was back in the day. Some varieties are naturally more HBL tolerant than others and these grafted onto a tougher stock will be within the effort level of the backyard gardener.
I asked about the ongoing GMO citrus trials and the results are looking very good with some totally resistant trees (PCR negative) thriving in greening infested locales. FDA and USDA will have to approve any release of these. That may take a long, long time.
The UF Lake Alfred website contains information about the rootstocks.

Anyone have any experience/advice in general? Anything that leaps to mind as far as pitfalls, etc?

Here is a Penn State study on plastic mulches that may answer some of your questions. Good luck...
http://extension.psu.edu/plants/plasticulture/technologies/plastic-mulches

Use phosphoric acid. Its second pKa is 7.198 which is close to your target pH of <6.5 - right where you want to be.
With a 150 gallon tank, you can learn how to make a phosphate buffer solution rather than paying big bucks for small quantities at a store. This will involve buying some potassium phosphate too. This should get you started - http://www.ou.edu/research/electron/bmz5364/buffers.html

Possibly the tree is (or was) growing quickly. Scale, aphids and sucking insects in general are attracted by the new growth. Any scale insects will overwinter unless killed or removed.

53^o here this morning.