HI John,
Welcome aboard. You have the mid-watch.
Bart has the coffee pot on down in the Goat Locker.
Rather than tagging along on another thread, you might consider starting your own. You will probably get more answers that way.
That said, welcome to the battery mafia. If your trees deposit a lot of debris on the track, a scale snow plow of some sort of other will be a big help. Or a leaf blower.
If you are concerned about scale in the garden, then code 250 or even 215 would be the way to go. If you think that the dog, or a deer or even you might step on the track, then give code 332 some consideration.
Is frost heave a problem in your area? If so, your proposed method of track laying has not proven very reliable. OTOH, if there is no frost heave, then there is not much to worry about. When the track is floated as you propose, you will find that on curves the outside track seems to sag a bit so that the train will lean to the outside of the curve. This is easily fixed by shoving some more ballast under the outside rail. There are other methods of track laying. You might give the ladder method a look-see. Just type in “ladder” in the search engine on this site.
Do you plan to sit back and watch you trains chase their caboose, or are you more into operating? That answer will influence your layout design.
Well, others will chime in and give you more to think about. Welcome to LSC!
SteveF