the main problem with HO cars on 1/32 track is that the pickups on HO cars are wider than the rails on 1/32 track. They'll be able to get current sometimes, but not reliably, especially around the turns.
Since you're making it yourself, you could use copper tape but set the tape wider than more normal 1/32 tracks are, such that most 1/32 car braids will still touch, and HO car pickups will also touch. The problem is that by trying to cater to both standards, neither will work optimally as they would on rails designed for their type of pickups.
1/43 cars such as those from Carrera Go! and SCX Compact, as well as Kyosho (the D-Nano people) D-Slot, and Ranch Design, WILL work on standard 1/32 type rails. Have you looked into 1/43 scale racing? A lot of people go that way because the cars are small enough to fit a good track in a small area, but detailed enough to appeal to their sense of "model car racing" without having that "buzzing bees" feel that magnet HO racing often has.
As for getting the analog cars to run on a digital track, since you're making the track yourself, you can install a switchable wiring system so that when you want to run analog, you switch it one way, and when you want to run digital, you switch it the other way. Each "way" being controlled by a dedicated analog or digital control system. Unfortunately, I don't know of any digital chip small enough to fit in any HO scale car, so you'll ONLY be able to run the HO cars in analog mode.
Are you married to HO scale in some way?
