For example, you say that 2nd gear is too low, requiring throttle to compensate when going down a hill, if I understand you correctly.
No, I said 2-direct was about perfect for descending my grade, I'd say 8-9% at the top, leveling off a bit, rest of the way about 7%. Nothing major unless you have 2 1/2 tons hanging out there in front of your steer wheels...
Also, I'm generally a complete slowpoke when on a trail, to the point that I've successfully climbed sand dunes in 1st gear low range. I'm equally slow with the HMMH, usually wishing for something lower than 1st gear, low range, when moving loads. And if I picture your situation right, the surfaces I'm operating on are perfectly flat in comparison.
Based on my guesswork, it sounds like you're going much faster than I would, using gears one or two steps up over what I'd pick, and on much rougher terrain. If that's true, it would explain how you can make the forks bounce up, have loads fall off, etc. A photo of what you're traversing might help me understand this better.
Fair enough. If I could find my 2nd, charged camera battery or the charger for it, I'd have taken some pics to post. Two problems I faced: one, running out of daylight; two, keeping a truck waiting which I wasn't expecting for another week yet. Even without being in a rush, 1-under, 1-direct, 2-under in low range are slow enough to get out-crawled by a baby. The gears I'm using are walking speed for a puppy, sometimes throttling up, my doggie broke into a slow trot now & then to keep up alongside. Slower than I can stay balanced on a motorcycle.
Going any slower, I'd have to think it'd be more cost-effective to offload one truck onto another, drive that truck to the jobsite, and offload it. Given the equipment at hand, and the amount of daylight this time of year in the mountains, if my HMMH is going to be of any value over the long term, you can't tell me 3-direct in low range @ 1500rpm as a top speed on good surfaces makes me some kind of hot-rodding speed demon!
Maybe if I were carrying ordnance, I'd go slower. But there comes a point where two dudes pushing a cart is more economical. I'd rather think that, even if downtime cost me some hours, less than half a day to transport five pallets that far across that terrain, must be economical somehow. Don't go bursting my bubble that at some point the HMMH makes sense in the final cost-benefit analysis!
I had to ultra-granny back up that hill at high idle (1100 in a HMMH) unloaded yesterday, crested the hogback just as she quit entirely, coasted down & parked for lunch. A load big enough to require that low a gear to move (2 crates on my spread contain 5 tons of disassembled 125-yr-old, 25hp steam stationary engine from a decomissioned Great Lakes lighthouse, seized but gorgeous) should come in on a flatbed truck. Or a 3-axle, 65-ton crane truck. That's the biggest thing can get to my jobsite, and just barely, which delivered those crates. I might build the quonset around them, instead of moving them in later. In 1-under, low range.
But that's a 50-yard move, not cross-country. In light of no damage or injuries, I'm glad I found the limit of my offroad forklift the hard way. Won't be doing that again! I made a stupid mistake, but other than that, descending @1200-1500rpm in 2-direct low range wasn't my mistake and I don't think it's inherently unsafe unless you're carrying too big a load for the HMMH. IMO after one day operating an offroad forklift, so YMMV as you write your own book on how it's done.
Which brings us to agreeing to disagree, which is fine. Still pics or even video aside, you kinda had to be there. I learn from my mistakes, so the takeaway here, is there are plenty of mistakes to be made with the HMMH forklift. Because the truck is way more capable than any other chassis any other forklift has ever been mounted to. Make your own rules! Safety first. Ratchet straps woulda saved me from exceeding the operational safety limit for the task at hand, even if it was only for a few yards. If I'd hit 2-direct as planned, never woulda happened. I was trying to get some actual work done, not take all day proving my truck could do it once if driven slower than a snail.