This is pretty much where I ended up on this.I'll admit, I'm not a huge fan of adding any extra naming and I'm leaning toward the side of keeping it simple. Without the "Harvester", you either have a Traveller or a Terra, and that may be enough.
I was thinking that maybe a play on Electrall to "ElecTrail" or something could work, but I just don't think it is really needed. Some details in the names (colors, letters, accents) could allude to the fact that it is all-electric, or add an "E" after the name as part of one badge maybe.
I think it makes more sense for legacy automakers to add an EV designation to model names, especially if they make that model in both ICE and EV variants. Examples of this would be the Ford F150 and F150 Lightning, or the Chevy Blazer and Blazer EV.
However, in the case of Scout Motors, they planned to be an EV maker from day 1 and the Harvester was the special submodel, not the other way around. Like how Rivian, Lucid, or Tesla just give their models regular names without a special designation that they are EVs, because it's known from the start that they are EV makers.
I must admit it was fun to think about names for the Scout BEVs, and I really liked the Electrall tie-in to IH history, but ultimately I think it's just not necessary. Also, it may already be too late. That ship may have already sailed. If SM was planning to have a designation for the BEVs they likely would have introduced it at the reveal event last year when they introduced the Harvester.