Question about recording a tas demo

Hello folks,

I'd like to ask you something. 

I'm currently using prboom-plus 2.5.1.1 and recording a demo using the tool "recordfromto xxxx.lmp yyyy.lmp -skipsec zzzz".

I'm only halfway done, but the demo is already over 40 minutes, so everytime it takes over 20 seconds to load the demo (and I'm dying a lot). So here's my question:

is it possible to re-record into an empty demo file (maintaining the stats) and in the end merge the demos together? I'm willing to change doom port if that's necessary. Otherwise, any other solution to this problem should be fine, I kinda hate to wait 30 and more seconds to play, just to die 1 second later.

I don't know if merging two seperate demos is possible. 

I would recommend to use XDRE (currently working on a tutorial for that) since it allows you to have control over each tick. The only thing with such long demos is to use savestates in XDRE, otherwise XDRE might take even longer haha. 

Thank you for your suggestion.

Sadly I'm only doing segmented demo for now, but I'll keep that in mind in case I'll ever try built demos.