Load 2015 PRO when have already loaded 2020 PRO

I have purchased a new computer so I have a backup if things go wrong and my old workhorse dies. This has happened to me before and I lost a couple of weeks work by the time I had everything up and running again. I am OK until my current (now 6 year old) computer suddenly dies. I am just trying to get my backup computer in a match ready state for the day it will be required. I want to load both 2015 and 2020 sketchup, but have problems. I know that you can have 2 computers with sketchup loaded as long as they both aren’t being used at the same time and I know that you can have both 2015 and 2020 loaded on the same computer. The problem is that although you can load a 2020 sketchup after you have loaded a 2015 and both still run, you cannot get a new computer and load the 2015 version as it is redundant once 2020 has been loaded onto another computer.
I need to load both versions due to my (possibly unique) workflow, which combines starting in Autocad, exporting the plan to Sketchup 2020, Making my model and setting scenes in 2020, doing a saveas to Sketchup 2015 and using 2015 layout to set up my pages, then exporting back to Autocad as pre set-up (A3) DWGS. I then create a new master Autocad DWG that xref all of these new DWG’s into its model space so I can note all the drawings up in model space, then set up paper space layout tabs to print from and add any other minor notations as required.
The Problem is that I need both 2015 and 2020 loaded to run efficiently. 2015 was the last version that allowed you the choice to explicitly export fully setup pages from layout to Autocad MODEL space. The newer versions deleted this radio button and it is now automated. With the new versions Vector based Elevations and sections by default go into Model space and raster perspectives get exported into Paper space. Under the pre-2016 version of Layout when you exported with the MODEL radio button ticked everything went into model space and in addition each page in your layout was exported with its layout into Autocad as separate drawings. Really handy if you then xref those into one Autocad drawing, as each time you alter your sketchup model it is easy to update the Autocad drawings by just reloading the xrefs.
I have tried workarounds in 2020 without using 2015 but it is much slower. For me the quickest way is to be able to do it the way I currently am.doing it. It is a pain having to keep remembering to back-save as 2015 but still better than just using 2015 as the 2020 version has removed a lot of buggy crashes that I had with 2015… All that being said if anyone has some smart solution to achieve my hybrid workflow just using 2020 I am more than happy to give it another go.as I really would like to retire my old 2015.

Not sure if I understood the issue, but are you having problems getting the license to work for 2015 while trying to install it, now that you have activated 2020?
If so, I had a similar issue with an older version of Layout and contacted Sketchup, and they reactivated my old license in order to install it on a new computer.

For the issue with the computers dying, we use a NAS (Network Attached Storage with RAID 1) to hold all the files, so if any of the computers die, we just connect a new computer into the NAS and are good to go.
We only lose the progress between the “last save” and the time the computer died. (This has happened a couple of times). There are a few options for NAS, so if you go with that, do some research.

I just tried exporting from Layout 2020 and it lets you choose “Export for Sketchup”, that sends all the info including title blocks to the Model space in Autocad. Is this the approach you mentioned to be slower to export?

Thanks heaps Fredy,
Problem solved. I actually feel pretty stupid at this point in time. My tired old eyes didn’t see the lightly greyed text explaining that “Export for Sketchup” actually was what I needed. It seems that I have been doing save back as version 2015 for years without knowing that they had just renamed the “Model space” radio button in subsequent versions… Seems that I can finally retire my 2015 for good. Yipee!
I had never heard about NAS until you mentioned it, so I figured I better do a bit of research on that as well. Really interesting… but probably on a cost basis I probably will stick with my old tried and true backup machine method. I looked into Mirroring at my last purchase (buying 2 identical computers at the same time and having one as a backup) and it seems that NAS is an advanced version of that. The fact you had to buy multiple computers (or drives as in the case of NAS RAID) simultaneously put me off. This meant that although you had great security they all aged together becoming redundant at the same time. Since I already had one machine that worked I didn’t feel like wasting it,so bought just one new machine with better processing power, and reinstalled all of my software on it. If a machine dies I still have one old machine at hand ready to go and just need to buy one new one. This way I am upgrading my hardware a bit more regularly and at a lower cost price. Before cloud storage this wasn’t really an option due to file storage issues, but since it is now so cheap I manage to keep costs down by storing files on the cloud and keeping a weekly backup on a solid state portable backup drive just in case of a ransom-ware attack or an unfortunate mass deletion.