If it is imperative that you maintain win10 then I understand your reluctance to put it at risk.
As for booting from the card reader, there could be problems too. I have a Lenovo which has LL3.8 installed on the HD and will boot from a USB SDHC card (F12 at powerup gives me a menu to select the boot device) but the built in card reader is not recognised as a boot device. A eeePC 901 will boot from the built in card reader so there are obviously pitfalls with some machines. If you can see some way of choosing the boot device (F12 maybe) I would be inclined to install LL to a SDHC card (class 10 for better performance) with Etcher and try it. If it doesn't work, I'm stumped!
Edit: I can boot the Lenovo from a SDHC card mounted in a USB card reader which is available in UK from Poundland stores (for £1), probably available in your $2 or $3 shops, but again you have to have the means to select the boot device at power up.
I hope you are able to overcome this problem, LL3.8 is worth the effort.
As for booting from the card reader, there could be problems too. I have a Lenovo which has LL3.8 installed on the HD and will boot from a USB SDHC card (F12 at powerup gives me a menu to select the boot device) but the built in card reader is not recognised as a boot device. A eeePC 901 will boot from the built in card reader so there are obviously pitfalls with some machines. If you can see some way of choosing the boot device (F12 maybe) I would be inclined to install LL to a SDHC card (class 10 for better performance) with Etcher and try it. If it doesn't work, I'm stumped!
Edit: I can boot the Lenovo from a SDHC card mounted in a USB card reader which is available in UK from Poundland stores (for £1), probably available in your $2 or $3 shops, but again you have to have the means to select the boot device at power up.
I hope you are able to overcome this problem, LL3.8 is worth the effort.
1) Lenovo T520 i5 LL3.8 8GB ram, fast & stable
2) Medion P4 32bit LL3.8 1GB ram, quite fast & stable
3) eeePC 901 32bit LL3.8 1GB ram, fast & stable
4) eeePC 701 32bit LL3.8 1GB ram, slower & stable but small and light enough to travel with me to New Zealand when visiting family in Blenheim.
2) Medion P4 32bit LL3.8 1GB ram, quite fast & stable
3) eeePC 901 32bit LL3.8 1GB ram, fast & stable
4) eeePC 701 32bit LL3.8 1GB ram, slower & stable but small and light enough to travel with me to New Zealand when visiting family in Blenheim.