How strong can a foamie cabinet be?

As I talked about in my other thread, I am building out a Hi Top camper shell camper instead of doing the wide body / king bed build I was working on. I no longer need a king bed, and I am needing to get things done faster so want to simplify and make as many steps as easy as possible.
The truck is a 1/2 ton F150 with not the full payload package, but many of the options, HD springs, trans cooler etc, just not the funny 7 lug axles / wheels. which is efectively the same payload as a 1970s 3/4 ton but we won't go into that...
Anyway in order to keep weights reasonable, especially since I am bringing cast iron cookware, and 4 7 gallon AquaTainers for my water supply. I am needing to figure out some ways to do the build light. I was thinking of the cabinets that I want to have enclosed and use as a bed frame / storage bench. Oh just see the tons and tons of builds on Youtube, you know the setup I think. Anyway I was considering using 2x2 framing and filling the void with foam and doing a PMF wrap on the assembly. I am thinking this would be lighter than plywood, but is it strong enough?
I am a very substantial man weight wise, at current 390lbs, so I need to be sure whatever structure holds my bed can hold my fat butt. I seriously doubt an all foam / PMF structure can hold it, but will the wood frame / foam / PMF do the trick?
Also is there any concern with mounting my charging center / inverter therein a foamie cabinet?
My electrical / charing center should look like...
ATEM POWER 12V 20A DC to DC Battery Charger with Solar Input MPPT Controller for Lead Acid, AGM, Gel, Calcium, Lion Batteries, Multiple Protection Design On-Board Charger. Yes I know Renogy is the preferred brand of many, but I have had Atem Power devices in the past and had good luck with them. And I do not need a 30 amp which is the smallest Renogy offers. I am basically powering a 12v fridge, a CPAP machine, my laptop, and USB chargers NOT all at the same time.
And a 110V inverter.
GISIAN 500W Pure Sine Wave Power Inverter DC 12V to AC 110V Inverter
I know it is a cheapie, I have a 500w modified sine wave inverter already but don't want to subject my laptop to it... And yes it IS more than the 300w solar suitcase can do, but I am figuring spreading the load should suffice. I might have to chage laptop on the generator if need be... (Laptop charger pulls 240w max).
The truck is a 1/2 ton F150 with not the full payload package, but many of the options, HD springs, trans cooler etc, just not the funny 7 lug axles / wheels. which is efectively the same payload as a 1970s 3/4 ton but we won't go into that...
Anyway in order to keep weights reasonable, especially since I am bringing cast iron cookware, and 4 7 gallon AquaTainers for my water supply. I am needing to figure out some ways to do the build light. I was thinking of the cabinets that I want to have enclosed and use as a bed frame / storage bench. Oh just see the tons and tons of builds on Youtube, you know the setup I think. Anyway I was considering using 2x2 framing and filling the void with foam and doing a PMF wrap on the assembly. I am thinking this would be lighter than plywood, but is it strong enough?
I am a very substantial man weight wise, at current 390lbs, so I need to be sure whatever structure holds my bed can hold my fat butt. I seriously doubt an all foam / PMF structure can hold it, but will the wood frame / foam / PMF do the trick?
Also is there any concern with mounting my charging center / inverter therein a foamie cabinet?
My electrical / charing center should look like...
ATEM POWER 12V 20A DC to DC Battery Charger with Solar Input MPPT Controller for Lead Acid, AGM, Gel, Calcium, Lion Batteries, Multiple Protection Design On-Board Charger. Yes I know Renogy is the preferred brand of many, but I have had Atem Power devices in the past and had good luck with them. And I do not need a 30 amp which is the smallest Renogy offers. I am basically powering a 12v fridge, a CPAP machine, my laptop, and USB chargers NOT all at the same time.
And a 110V inverter.
GISIAN 500W Pure Sine Wave Power Inverter DC 12V to AC 110V Inverter
I know it is a cheapie, I have a 500w modified sine wave inverter already but don't want to subject my laptop to it... And yes it IS more than the 300w solar suitcase can do, but I am figuring spreading the load should suffice. I might have to chage laptop on the generator if need be... (Laptop charger pulls 240w max).