NEVER ground the panel to neutral!
The idea you mentioned of switching roles, attaching neutral to the panel chassis and isolating ground, is a terrible idea that will send you to jail after it kills someone. Neutral wires break all the time. When they do, neutral is energized at 120V - that's why it has insulation!
If you tie neutral to the enclosure, then when neutral breaks, the enclosure WILL be energized at 120V. What are the chances of the tenant touching the panel right then? Well, close to 100% since their power is out and they're trying to figure out what's going on! This borders on "booby trap" lol and is so severe many DA's would go criminal on it. Given it's a textbook example of a slumlord creating a hazard by pinching pennies on equipment and doing illegal, unsafe DIY. They'll make an example of you.
Yes, it's illegal for landlords to DIY on properties intended for rental. Your requirement of a meter is prima-facie evidence of intent to rent out. With that comes the duty to have a licensed electrician do the job.
This particular box cannot be used!
As discussed, it is labeled "Service Equipment Only" and cannot be used as a subpanel. That will be true of essentially all "combo" equipment on the market.
But I don't understand why you're using combo equipment. You seem to be motivated by "cheap", as apparent from the very small panel... and all-in-ones are specialty items that are more costly than a generic random plain meter pan + a random plain breaker panel + 2 inches of 1-1/2” steel conduit.
Also, all-in-ones are unnecessarily restrictive on panel spaces. You really ought to have at least a 30-space panel on a dwelling, and with plain panels, that's only a few dollars more.
Why a plain 4-jaw meter pan works.
4-jaw meters do not attach to neutral in any way whatsoever. They provide a pair of courtesy neutral lugs which are grounded to the case, but what do we put there? Hmm, let me think - ahh, yes, ground! The neutral can be run right through it without stopping - either in a continuous wire run, or a Polaris connector.
If you have a 5-jaw meter, get a 4-jaw meter.
Also plain meter pans are "on the outs" due to NEC 2020 requiring meter-mains for services. Not your problem.
Consider putting the panel indoors
Since this is a subpanel, NEC 2020 doesn't require a disconnect on the outside of the building. It does require a disconnect but it can be indoors. As such, you need a main-breaker panel (as the cheapest way to get that disconnect) - but you can mount the whole shebang indoors.
Indoor mounting also keeps the costly GFCI and AFCI breakers out of the weather. If you picked a 10-space panel thinking "oh, I'll just use mostly double-stuff breakers", bzzt, not anymore. NEC 2014 required huge numbers of A/GFCI breakers and it's gotten worse and worse on NEC 2017, 2020 and 2023. So yeah, a 10-space panel isn't going to happen. And an "all-in-one" large enough will be VERY expensive.
There's a reason it was on clearance lol.