for such a high work-load i wouldn't suggest anything by landoll that is gas/lpg powered. forkinlift is right on the money with this one. The only reason landoll designed a gas/lpg powered truck is to compete in the market for those type trucks, but they have a long way to go to get thier units competitive with the other brands effectively.
Their best trucks are the electrics but even those have thier own set of problems in high workload environments. Not to mention they require special training to operate, they do not drive or steer like any other machine and can be rather hard to get used to working in the tight spaces they are designed to work in. Oh yes, anyone that has serviced a gas/lpg powered one knows they can be a pain to service too ;o)

For thier design and application the electrics are pretty good under medium to light workloads imo.