And welcome to the club...
Mr Titmuss' method to mimic a baroque guitar is indeed a clever and cheap way to play baroque guitar music the way it should be, but be aware that this "double re-entrant" tuning (i-e with the third string being the lowest one) is only effective for the music of Gaspar Sanz, which makes great use of campanella scales.
The most common tuning is the french one, with a re-entrant A and octave strings for the fifth course, which means d-D. With this tuning, you can effectively play virtually all of the baroque guitar repertoire, and that's the main interest of having courses over single strings : you can choose which string you pluck in a course, in order to fit in the melodic movements of the music.
That being said, tweaking a regular CG the way you describe is still a good option, but for those who don't want to make this time-consuming modification on their regular instrument there is another solution. I recently found out that two traditional instruments from the Canary Islands are strunged and tuned almost exactly like a baroque guitar : the Timple, which is basically a 5-string tenor uke, and the bigger Rajao (closer to a baritone uke) are both cheap alternatives for a baroque guitar and make wonderful spare companions.
Please have a look to this exquisite rendition of Santiago de Murcia by the great Hermann Vandecauter on the rajao:
I have a good baroque guitar, but I enjoy sometimes playing my timple on the sofa, watching TV for instance. Two different feelings, one being "the real thing", the other more of a cheerful and light way to experiment campanella scales on an fun instrument that fits any luggage; a very convincing "baroque travel" companion.
Hope this helps,