I think the reason why there’s the 63 MB limit in Magic Dsbox is the same as in the official Windows Dosbox: himem.sys only supports up to 64 MB, so anything above that is really experimental, and likely to cause instability. Looking at Dosbox Turbo, and how crash prone it is, that might be one of the reasons.
Is there any way to reduce the RP install size? Like e.g. chose lower texture resolution or something like that? Or maybe you can use an older version, like 1.2, or 2.2?
It’s pretty weird RP needs so much RAM, when Half-Life only needs 24 MB, and Thief and Diablo 2 run fine with 32 MB. ?