The iron upgrade does indeed open up the #45 more so than the stock iron.
No, it's not a faux pas to mess with the enclosure design. We use the plate and base method because it's incredibly easy to go back in and fix issues or apply modifications down the road compared to having components mounted to multiple panels at different angles. Here is an example of a pair of Paramour monoblocks that I converted into a stereo amp.
You can get binding posts intended for speakers and just install them through the wood base. I sell a metal plate and IEC power entry module on eBay that can be installed into wood with a hole saw and some wood screws. To move the RCA jacks to the wood base, I install the RCA jack on the biggest fender washer I can find, prewire the RCA jack, drill a hole in the base, then use polyurethane adhesive to glue the fender washer to the wood. If you have an oil finish on the base, you'd need to sand it off first.