Hi David, i think you will find the little trailer sailer great. I have been on a ultimate 18 and it was a fairly roomy boat for an 18 footer, so i would imagine the 16 will be OK.

Getting the mast up on trailer sailors can be made easy with a bit of thought. Have a look at the trailersailer place forum. Those guys are all over it. I get a big heavy 8m mast up and down by myself with a method pinched from that site, so i am sure you will find a way to get the stick up and down on your 16 footer without busting your back.
I would guess a short shaft outboard would be the go on such a small TS, depends what type of OB bracket it has, could most likely move down or add jacking plate if required, so not a huge deal. I think the little 3.5/3.3/3hp tohatsu/merc/ mariner (all the same with different stickers) would be only just adequate to power your boat. I have one and they are great little motors but with the props available for them not really suited to heavy displacement boats. No reverse, just nuteral and forward. You can spin them to reverse but maybe not ideal for you to be reaching over the transom with a bad back.

I dont like small 4 strokes and don't think a 2.5 would push your TS (i have a 2.3 honda). I have found 4 strokes under 6 hp to be heavy, loads of vibration, complicated and tempremental, but some people like them.

My choice would be a 5hp 2 stroke. Yamaha or
tohatsu/merc/mariner. No longer allowed to be imported, but there should still be plenty around. The advantages are you can get props more suited to displacement boats, remote fuel tank and likely good reliability being very simple motors. You do have to mix fuel though.
Enjoy your new toy.
Cheers Neil

Hi david
It looks like you are going to have to work this all out by yourself (unless someone jumps in soon).
Not to worry.
As Neil (Wallymullet?) said trailersailerplace www.trailersailerplace.com.au/ is the place to go for specifically your requests.
A few of the posters there are on the Gold Coast.

There are a few different mast raising methods, but yours should be pretty easy to deal with (light!!)

2 stroke outboard are reliable. proper maintenance is the key (water pump impeller, spark plugs, correct fuel oil mix, ) and a used engine in good condition will do you well.
With a boat that small if there is any wind at all you should be able to get where you want to go (not in any hurry though)
I have a 25 footer and the engine goes off as soon as I have any motion at all.

For a boat ladder you can try Gumtree or you local boating store. They are not so expensive.

gary