I have started with win 10 on a GPT disk, in my Lenovo ThinkPad L530, and ended up with a usable win 10, with ArcaOS 5.0.3 installed (any version of ArcaOS should be okay, once you get the disk converted, but later versions are better).
First, READ every word in all of the PDFs, and TXT files, in the root of the ArcaOS ISO. You may need to burn a DVD to be able to do that, although you may be able to mount the ISO in some operating systems.
You must be sure that the system has BIOS support for what they call CSM, and it must be enabled. In the L530, it is in the BIOS settings under STARTUP. I have it set for BOTH, with Legacy first. After doing that, it should still work with a GPT disk installed. Apparently, not all new systems have CSM support. If not, stop here, and wait for the support to be done for ArcaOS (not even started, yet, AFAIK).
You need a full backup, that has been proven to actually restore properly (I will talk windows, but every other OS must do the same). The only backup program, that I know of, that actually works with windows, is Acronis. If you have a Seagate, Maxtor, or Samsung, disk in the machine, or attached by a USB adapter, you can use the free (limited) version called Seagate Discwizard (google it). I haven't checked lately, but Western Digital also had a free version of Acronis, that only works when a WD disk is present. This backup must work on the file system level, you cannot use the DFSEE disk image feature, because it will put the data back exactly as it was backed up, and that isn't what you want. I am not sure what Acronis does at restore time, but it fixes windows so that it will boot. NOTE: that you may need the smaller windows boot partition, if you use something like security software. For a simple windows install, you only need the (windows) C: drive. Do NOT restore the boot records.
Next, boot the ArcaOS installer from a USB stick, or from a burned DVD. Depending on the system, this may be difficult. Each one that I have, does it in a different way. The L530 gives you about 1/2 second to press enter to interrupt the boot sequence. Once you get there, one of the options is to press F12 to get the boot device list. Select the ArcaOS USB stick (you can press F12, to get to the boot list, without going to the first menu). Note, that the boot device list may have two entries for the stick (or DVD), one prefaced by UEFI, and one not, You need to use the one that is not. Once you get the ArcaOS installer booted, use the System Management-> Disk-> Disk Utility program to wipe the disk (effectively removing everything that is on the disk). Ignore any errors, and select the Disk-> Wipe disk information-> All... option. REBOOT to the ArcaOS installer (again, don't use the UEFI one, if it exists). Run the Disk utility again, and follow the instructions to add LVM information, REBOOT, and use System Management-> Disk-> Manage Volumes (Graphical) to build ALL of the desired partitions (including whatever you need for other operating systems). AND add the Air Boot boot manager (the old Boot Manager can be used, IF, and only IF, Air Boot has some sort of problem that can't be resolved).
Do not, ever, let any other partitioning tool do anything, or it will likely cause problems. The Disk Utility program is a special version of DFSEE, that is specifically designed to do partitioning correctly. DFSEE itself, can do it correctly, but only when it is running under OS/2.
Now, you can restore windows, and it should work (assuming you have a good backup to restore).
Install ArcaOS, and it should work.
Hopefully, I didn't leave something out. Ask questions if something doesn't seem to be right.