Hi David,
If you really wanted to then you could render out a half res (or lower) proxy in prores, edit, and then reconnect the full res prores versions of the footage used at the end. The problem is that you are trading hard drive space for time and potential frustration. Both of those cost you money, it’s up to you to see which one is cheaper.
You can also (i believe) set ins and outs in the log and transfer window if you know what selects you specifically want.
Lastly, I would say that the external drive speed isn’t necessarily all that important. That ought to open up the options a bit. Also, how large is your internal laptop drive? That’s generally a pretty cheap/easy upgrade.
I hope this helps,
Ross
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