Hi Cris,
I started out playing with trains about 30 years ago.
I built an indoor HO scale RR with 2 mainlines, sidings, a switching yard, tunnels, ect. When the track was clean, it was fun, when not it wasn't. I just got tired of all the reaching and stretching and trying not to make more work for my self while cleaning and polishing the track.
When I decided to to build my outdoor RR, I decided it would be trouble free. So after much research, I decided to go with battery power and remote control.
I just looked online at some higher amp transformers/track controllers and was amazed at their cost.
I have 2 big Hauler 4-6-0s and a 2-4-2 Lyn. that I have converted over to battery power. To convert the first one to battery power was about equal to the cost of a high end power supply. After that, it's just buying another battery and receiver for the other locos.
I'm running 14.8v battery packs from All-Battery and Crest Electronics Train Engineer.
You said your hubby was a mechanic so he must be mechanically inclined. With all the info. on the web and this site (look up Loco Bills threads on battery building and remote control), he should have no problem converting your engine over to battery.
I run my locos for at least 3 hours strait on batteries and there is no jerking or stalling or slowing anywhere on the tracks. I never have to clean the track except when debris fall on it or plants grow over it.
Speaking of track. Another money saver is aluminum track. It costs a lot less then brass or stainless. Did I mention I never have to clean it

One other benefit with battery power is there is no need for special track wiring for turnouts, loops or whys.
I truly enjoy running one train nonstop, on the mainline, and switching cars with another. Or, pulling one train into a siding while pulling another train out.
When I built my garden RR, I decided I wanted to enjoy it. Half of my fun is building and improving it, the other half is running it. There is no third half for track cleaning.

This is just my opinion and there are many others out there. All I know is that I'm very happy that I took this rout.
Garden railroading should be fun and relaxing and you should only have to work hard at it when
you want to.
Enjoy your garden and railroad!
Adam