the price will be higher than the RBM33G + Chassis.
It depends on the price of the GPS (which is part of the LtAP) and the price of weather protection of the RBM33G+chassis - I assume at least the GPS and LoRa antennas will be outdoors, and antenna cables shold be ASAP (S=short in this case).
Btw, there are several significant differences between LtAP and RBM33G although they are built around the same MT7621: LtAP has the single USB3.0 port routed to the miniPCIe slot, so only USB2.0 is available at the external USB connector; on RBM33G, the USB3.0 is only available at the external connector, not on any of the miniPCIe slots (nor the M.2 one).