I've tried it - about 8 months ago - laborious to focus and to get maximum intensity you have to orient your enlarger towards the sun which is awkward to say the least ...

I gave up and decided to build a 4x5 large format instead ... in which funnily enough I've also put in cyanotype sensitized paper to get cyanotype negative prints, it may well be worth making a similar system as an enlarger but out of much lighter weight materials as found in field cameras, pinholes etc...