You CAN patch IOS36 on 4.3 FYI. Use the TBR mod (I think its called TBR 1.14) which uses HW_AHBPROT to patch IOS.
But a much better solution would be for Gecko OS to be upgraded to use HW_AHBPROT to do its work instead. However, the problem with that is that IOS need to be reloaded in the channel loading process, losing HW_AHBPROT (although apparently there is some way to do it without losing HW_AHBPROT), so that makes life harder.