Note all that clatter in the rack over the rear gate--those are the pole sections used to build the frame for that COC (command Operations Center) tent (the big lumpy honk of plastic is alleged to represent the rolled-up tent. Note that the tent is far larger than a single M-577
A person could quite easily use metal clothes-hanger wire to support a model COC tent. These are usually closed-up in practice, for light discipline as much fad for anything else.
A person with a fulsome budget might get silkspan in the RC airplane section of the hobby shop; using the sort of tissue paper clothing is packed in will often suffice.
When the tent is deployed, the racks ought be empty--although some spare sections of tent tubing can be shown "spare."
If a person wanted more interest with that 577, there are several ways. One is to use those "pallets" as a surface upon which to have the table & chairs sat upon. Note for diorama purposes, there ought be a number of lay-abouts lurking outside the COC tent, quite a few of which will be toting various back-pack radios (PRC-25/77 mostly). Since the tent will have "brass" within, the runners and hangers-on have to be able to spring to attention on short notice, so crouching or kneeling positions are better than seated (anyone smoking ought to be shown doing so as discretely as possible, too)
Oh, and the curved pit on the roof deck is a davit, which fits in the square lumps on the right front of the "bump up"--this is used to hoist the generator to and from its position there on the center front. This can be set up for visual interest. Which is handy for using a bent-over crewman in a CVC monitoring said genset.
One of the better accessories for a 577 dio is 4-5 M-151, at least one of those with a cargo trailer full-to-bursting (under a bulging tarp) with all the gear a COC needs but "the bosses" do not wan 'seen' on the command vehicle.