No offense but 600lbs at the 4 to 5 foot he stated is well with in the capabilites of an L series. If he jumps up to a mx or m series he may as well get the off road forklift, as you just lost the maneuverability of the smaller compact tractor. Add in inexperienced operators and your begging for issues. Not to mention the emission side of things and worse visibility of the larger tractor. See how this all snowballs by going bigger? Better stability for 3 feet of movement to load/unload a truck doesn't make any sense imo.If you’re moving pallets up 5-6’ high, go for a larger more stable tractor and ballast the rear wheels and have weight on the 3ph. I know a smaller tractor will lift the pallets your are describing, but a larger, heavier tractor will be more stable. A Kubota MX series or other brand equivalent ( or larger) will give your more stability and less pucker factor.