A thought or two:-
- Whatever you've flown before, this is almost certainly draggier and lighter, and may well have less well sorted handling qualities. Get yourself trained in flying a similarly configured ultralight by an Ultralight or Microlight instructor, and also if you are used to "conventional" aeroplanes a good solid briefing on meteorology as it affects ultralights.
- Don't renege on your promise to yourself to get some floatplane training.
- Your LAME may well not understand the engine fitted, talk to a local ultralight club who should know somebody who understands whatever type of engine you have and can both check it over, and advise on how to treat it well.
- Having done those, get somebody to fly it first who is experienced ideally in ultralights, test flying and float flying. Then get them to check you out in it. The local clubs or national ultralight association wherever you are should be able to offer some advice here on who is trustworthy.
- Having done all that, I'm pretty certain you'll have great fun in it for very little outlay, it looks tremendous fun (and I speak as a well known connoiseur of very small aeroplanes, my record is a total take-off weight of 350lb).
You may well spend all you saved on training, but I think it's likely to be worth it.
If it helps your confidence, I've probably 60 or so separate homebuilt microlights in my logbook, albeit mostly in the UK where things are more regulated than most places. I won't claim that the experience has been universally uneventful, but I'm still here.
G