This is why I leave the couplers open on the ends of my trains, and all steam locomotives get the claw installed on the front (Where it is possible.). So if one does happen to catch up, they'll just couple, and now it's a trains with distributed power (Ignore that caboose in the middle.). With my Legacy system to Lionel for repair, I had to run using my Cab-1 and TMCC base last night. After getting my heavy Mikado and 10 Wheeler going, they went round and round for almost an hour without getting close. It's so relaxing to have a couple steamers going at once.
As for the OP's helices, if they are Legacy, then keep the cruse on and they'll go uphill, downhill, straight, and curves all at the same speed. If it were me, I would limit that loop to only command (Legacy and or DCS) locomotives of the same system and set them at the same speed and just make sure to check on them every once in a while, say like 30 min or so, and you'll be fine without needing extra fancy things to space them out.
I'm not sure how the sensor tracks could help you unless you write software that keeps track of the time stamp of when a locomotive passes over it, and then the time stamp of all the others in the loop as well as the time to make a loop, then calculates the train speeds and notices when a train is getting closer to the next, at which point it'll have to know which sensor track the faster train will go over next, and when, and then it'll program the sensor track just before that faster train gets to it so that it gets told to go slower. And the software would have to have speed curves for each locomotive to know what speed to set it too, or it'll just keep noting and adjusting the speed with every other sensor track pass. Not saying it can't be done, only that it'll require a very good understanding of programming, and having the Legacy command set which Lionel hasn't released (They've only released the TMCC command set.).
