It’s funny the comments on storage, typically a Popup has tons of storage due to the entire under bunk area being used. I wonder why these don’t?
I'm only aware of one lightweight, offroad pickup camper that has underbed storage and that is the FWC flatbed (though there may be a few of the small startups that are doing it in some models, too). None of the FWC slide-in campers have it; only the flatbed models. You typically only see underbed storage on the much heavier and more "travel" oriented slide-ins. Like all things, it's a trade-off. I don't know if Overland Explorer has explored that feature, but it would add a fair bit of height to the closed (and open) camper. For every inch of underbed storage, it would increase the height of the cabover by that much plus the thickness of the new floor. So I'm guessing a 5" deep storage would be about 6" more height in the cabover (and sidewall). That would add a fair bit of weight (6" more sidewall all the way around) and push up the center of gravity even higher since the roof would be 6" higher than now. It would also make the overall closed height and cabover 6" taller so less aerodynamic and harder to get under branches on forest service roads and urban obstacles. The closed cabover height is about 18" currently (not counting vents, roof rack, etc.) and I can't image having another 6" of height when closed for a total of 24". Would look and act like a hardside going down the road or trail. So all about trade-offs.
While many owners would welcome more storage, such as underbed storage, they would not be willing to trade the increased weight, height and center of gravity for it as you are now getting away from the primary mission of small, light slide-in pickup campers. I fall into that group. That extra height starts getting into the cons of a hard sided camper yet it's still in a softside pop-up so none of the pros (except the storage). If those buyers that would still want the underbed storage, even with the added weight and height, aren't the vast majority, it may never come since, if it was optional, it would require OEV to have two different templates and stock not only different rear, front and both side panels, but also different aluminum extrusions. And perhaps even a shorter popup canvas (unless they would reuse the current and then inside open height, or better or worse, would be super tall). Such features, options, height and weight may be features/options of the next class up which is the upcoming OEV BASE-CAMP.
I, personally, love the idea of underbed storage, but am absolutely not willing to add height and weight to get it so it's a 'no go' from that perspective. I have the CAMP-X pop-up for the low profile and relatively low weight and if it was 6" taller and heavier, I likely wouldn't have considered it. Just my opinion, though, and we all have a different use case and so different needs and wants. And, as the OEV operation increases, they may have the size and capacity to have optional structures to facilitate such options.