Use WinToFlash to install Windows on a USB enclosure with SSD.

Its only limitation is you need paid version to install Windows Professional, Education & Enterprise Editions.

Windows To Go is very slow compared to normal installation.

Of course, the best solution is to swap the HDD with SSD.

Also, keep in mind that many (cheap) USB enclosures do not support TRIM/UASF.

I used this one and TRIM works on it.