There is Pismo File Mount out there... It can mount a file as a folder (.ISO, .DAA, .7z, .zip, .rar, .pfo, etc).
And if the format of the file admits Write mode, it let you add, delete, etc.
It makes the whole Windows see that file as if it were a folder.
Sorry, for ISO-only read mode... so to edit the ISO image, instead of copying the whole content (aka, extract) you can directly mount it as a folder, the use imgBurn to create a new ISO with files from that folder, do the edits you need, etc.
You will only need free space for the new ISO file size, no need to have a lot of GiB.
Sample: All wsusoffline (32 & 64 Bits) for Windows XP, 7, 8.1 and 10 (ten folders). I want each OS and each version separated on its own folder, takes 34 GiB, putting them on ISO with imgBurn (activating the option for detecting duplicates files and compact the ISO image) takes only 25 GiB, earn 8.5 GiB of gain.
If you consider to pay... PowerISO is a really good option, and it also can create .DAA (a special format that can have LZMA2 compression and encryption at the same time), so for things that will be not modified in months is great.
I have all Windows CD/DVD images in .DAA format (a gain of 50% to 88%) and a lot more things on such format.
For Linux, Pismo has a version and PowerISO only has a free command line version.
I miss / want imgBurn would have the same option as PowerISO, open an ISO image, do the 'edits' and re-save as a new ISO image (without loosing boot, 'compact duplicates', etc.), but I simulate it with Pismo (I mount the ISO image as a folder), but that leads to a bootable loose if I do not put it manually.
Not to mention that a lot of ISO image I have (some with 'multi-boot') are non ElTorito, and for them I am still searching for such a tool that let me not loose such boot mode.
Also I have a pair of DVDs that has a so special format, that Windows can understand them... they act as a full HDD, with partitions, yes with partitions on a DVD... inserting it on a Windows machine makes more than one letter to appear... one of those is a DVD-RW, and I can write files on it (in Windows) without installing anything special, just a clean fresh install of Windows XP, and I can write files in one of those letters, but not on the others. It acts like a HDD with more than two partitions (one read-only, one read/write, the other is like a temp; you can write to it, but writes get lost after ejecting the DVD). I know that is so strange, most do not ever save it... On Linux the disk is seen very poorly. It sees all the partitions on the DVD, but it can mount only one at a time and no writeable only in read mode, and the one like a temp is not even mountable.
So not all ISOs are 'ISO9660'; some are weird. I do not pretend to 'edit' that ones so weird and rare... but I wish the standard ones would be 'editable' (do not confuse with writeable)... I mean, open an ISO image file, tell the application what want to change (in RAM), then ask the application to re-save as another ISO image file, but not losing ISO image properties like boot, multi-boot, HFS systems, etc.
Till now I only found partial solutions... no application to do it all in one application, sorry.
Remember: Pismo File Mount helps a lot, also any daemon tool or virtual CD/DVD, but what about the boot part? And what about special filesystems (not ISO9660, Joliet nor UDF? That is another story.