I replaced my RMD 8550 two years ago. I believe I had the double door version of your refrigerator. Check to be sure that dimensions are similar but the dimensions I saw were.
RMD 8555. 190. 1245 x 525 x 625. RMD 10.5XT. 177. 1245x523x605. MES
I installed a Dometic RMD 10.5XT. Soon after Dometic stopped selling the 10. But since then, they have placed it back on the market.
I did the install myself though I needed help physically removing and installing the new model. There are some excellent instructions on this form with precise steps and photos. It took a couple of hours.
I could never justify the cost, work and payback to install all the solar, lithium and controls for a compressor refrigerator.
After two seasons of use I would say the RMD 10 is a very good refrigerator. Gas, 12 volt and 120 volt - not like the POS 8550. It works better.