I have the 11.5 minimal build since last morning and booted into system and then back to recovery and used the nikgapps stock with config(not a personal build) and it has gone fine. Booted and worked good. Am sure mine is bigger than your build as I removed only the playstore installables, except AOSP substitutes and Google photos .@kdrag0n
Massive effort, thanks so much for all your efforts, not just a new build (massive changelog, love the detail), but a new website...
Update: I used to be able to flash my own GApps on Proton, in fact it was about the last ROM that reliably allowed this, but this build doesnt....im actually using my smaller 700Mb NikGapps custom build (i used to use the fill 1.2Gb one with config file) with no issues on 11.3.3. Might haven mentioned im no fan of GApps included ROM's, they waste too much of my data allowance to update them as the included GApps are always old. Is there any reason why i can no longer flash my own GApps? Yes im aware im probably the only person who complains about this, but i think its still a valid question about whats changed thats now making it fail
Could it be possible that your automated customised build is messing with the space left. The ROM is so bare that it shouldn't give any space problems.