It's looking good, but I think there are a few problems here.
First of all -- and most importantly -- the UVB.
UVB does not pass through glass or through most types of plastic/acrylic, and Plexiglass is a form of acrylic. There is a type of acrylic that is UV transmitting (rather than UV filtering), but it is quite expensive and unless you have specifically asked for a UV transmitting Plexiglass then your top will prevent the UVB from reaching your tortoise.
A second problem with a plexiglass top is that you will effectively have created a vivarium (in the sense of it being an enclosed box). You might just get away with this because your enclosure is so big, but basically tortoises are ectothermic (they need outside sources of heat to regulate their body temperature), and in order to properly thermoregulate they need a good temperature gradient in order to move frequently from cooler to warmer spots in their environment. So you want a warmest spot of about 86F or 87F and a cooler area of about 68F. When you have a sealed roof on your enclosure it is difficult to get that temperature variation. An open top is far better, and tortoises prefer an open environment with an exchange of air (it's always good to think how they live in the wild).
Secondly Hermanns tortoises, like most Mediterannean species, do not need a very humid environment. In fact they should have a rather dry environment with some humidity, and that is usually achieved by spraying the substrate with a light water mist every couple of days. I have Horsfields and once or twice a week I pour some water on my substrate (which is about three or four inches deep), and mix it around, but I only put in enough water to make it the teeny tiniest bit damp. It is very important that it is not wet at all, and should only be the slightest bit damp, and I leave one area dry so that the tortoises can choose that if possible. Also, of course, if you have a sealed top on your enclosure,the humidity will build up and run down the sides and this would be very bad. Because you are using a cyprus mulch as your substrate, there is also the possibility that if it is too humid then mould and fungus could grow in your substrate, so you do need to be careful, as mould or fungal spores can be dangerous for a tortoise.
Regarding humidity levels, there is a difference of opinion, but I think that for a Hermanns around 50% should be fine, and a light spray every day or two should accomplish that. Humidity is more important for hatchlings and young tortoises that for adults, and some people recommend keeping the general environment fairly dry (not totally dry), but building a humid hide for the tortoise to go into. This can be accomplished by affixing a moist sponge or some spaghnum moss to the roof of the hide and keeping that moist. Editha Kruger has some interesting ideas and if you google' Editha Kruger, moist root shelters' you will get links to the pdf of her article. It is also a good idea to bathe your tortoise several times a week in warm water that comes up to his chin (or where the top shell meets the bottom shell), in a container that he can't see out of, for about 15 to 20 minutes, and that way he can rehydrate.
I think your set-up with heat and light sounds fine. The UVB bulb will provide heat and light, and is your basking bulb just an ordinary household bulb that provides heat and light (but not UVB)? That sounds fine, but remember that UVB bulbs only last a year or two before you have to change them (the light still comes through, so you unless you have a uvb meter you won't know that the uvb isn't getting through. What happens is that the UVB gradually causes a coating to be built up on the inside of the glass of the bulb, and eventually that coating will stop the UVB from getting through, even though the light does get through. Will your tortoise also have an outdoor enclosure? The UVB from the sun is the best source there is, and they do love being outdoors.
Regarding food. I know that many people swear by Mazuri, but personally I prefer a diet of natural foods for my tortoise, and many commercial food is way too high in protein (not sure about Mazuri). Tortoises need a high fibre/low protein diet and weeds and other plants are by far the best source. On our website you can filter the database (which has over 1,000 entries) to just show plants that can be fed freely or in moderation to your tortoise and they do love pulling at leaves and flower petals, etc. when eating. Here is a link to the How to Use the Database section of our website, and if you scroll down there is a section on how to filter. https://www.thetortoisetable.org.uk/pla ... Mv_TKR7m9s
We have lots of people who live in the USA who prefer a more natural diet for their tortoses, and it is relatively easy to find a variety of plants to feed to them.
I really commend you for doing all your research and putting your set-up together before you get your tortoise -- so many people don't and they end up with problems afterwards, so well done for working so hard at this! You probably already have a good care sheet for Hermanns, but if you don't then here is a link to one: https://www.tortoise-protection-group.o ... 014New.pdf
It's aimed at UK owners but applies equally to tortoise keepers in the USA (lol, except that you have a better climate than we do).