Like the Pioneer document describes you need ~70KB of free RAM for a HP42S ROM Upload.
Calculator which are fulfill this are
- HP48G+
- HP48GX
- HP48SX with merged 128KB RAM card
The problem is that the HP48G+ is quite rare so it's often cost more or the same as the HP48GX. IMHO early HP48GX manufactured in Singapore with ROM rev. R are worth to buy. Some people swear on the latest ones with the black display from the HP49G. But I think most agree with me that the one manufactured in Indonesia are the worst one.
When you aren't a fan like me, buying a HP48 from the S series isn't such a good idea. Most software written in SystemRPL in the last years don't work on a HP48S(X) any more. Because I use an emulated HP48SX for my daily work, I take care that I write software working on the S and G series, but that's definitely an exception.
But back to your problem, some like you had the same problem only having a HP48 calculator with 32KB RAM. Two years ago I decided to publish a modified Clamshel.txt file describing also uploading a HP28 ROM image in parts to a HP48.
For the Pioneers it's much more difficult, but nevertheless, I wrote such a document describing a Pioneer ROM image upload in parts in January last year. But I wanted to avoid any questions to this complex process, so I decided not to publish this document. I you still want to try it, download the latest version of the CPROMUPL.ZIP package and drop me a mail over MoHPC for request the latest Pioneer upload document.
Cheers
Christoph
