That's great, but honestly if you haven't gotten him into the larger enclosure with a stronger UVB tube (if it's going to be or already is a large, wooden enclosure, you must go to a much stronger T5 strength UVB tube mounted to the ceiling, that must also have a metal reflector inside the tube fixture and behind the UVB tube, so that the
UVb light is reflected throughout the large enclosure, and he must have at least one Basking Spot/Platform that puts him within at least 11" of the T5 strength UVB tube; this is why you cannot use a T8 strength UVB tube inside a large, wooden enclosure, because the Basking Spot/Platform must be at least within 6" of a T8 strength UVb tube, and it's usually very difficult to accomplish this inside a very large enclosure), then I highly recommend taking 15 minutes to get the T8 UVb tube and fixture strapped to the underside of the mesh lid!!!
I understand that you're building him a larger enclosure with a T5 strength UVB tube, but the fact is that he has not had any adequate
UVb light at all if he's been under a T8 strength UVb tube that is being blocked by a mesh lid. Seriously, desert reptiles depend upon at least 13-14 hours every single day of strong, adequate
UVb light, and even though you stated that he can get within 4" the current T8 strength Reptisun 10.0 UVB tube, it doesn't matter how close he can get to it because it's not a strong enough UVB tube to emit ANY adequate
UVb light on the other side of the mesh. So he's gotten pretty much no adequate
UVB light at all for as long as he's been under that set up, and even when you get him into the larger enclosure with a T5 strength UVb tube that is within at least 11" of him with a metal reflector that is on for at least 13-14 hours a day, that is not helping him right now, nor will it completely reverse any damage already done by the total lack of
UVB light.
I'm only telling you this because
UVB light is so important to Bearded Dragons, their entire survival and all of their daily bodily functions, most importantly their digestion, absorption, and processing/use of any nutrition they eat, both from food and any calcium or multivitamin supplements you give him, are TOTALLY dependent on him getting 13-14 hours of adequate
UVB light every single day, and your dragon has not gotten any as long as he's been under a T8 strength UVB tube that is blocked by a mesh lid. Even the time since you first wrote this post until today is far too long for a dragon to go without adequate
UVB light, and is doing damage and weakening his bone density every day...so please, take 15 minutes and either gut the mesh out from underneath the length of the T8 UVB tube, or simply poke 4 tiny holes in the mesh lid (you can't even see them once you poke them in the mesh, it almost self-seals) and use twine, wire, string, large plastic zip ties, shoelaces, etc. to strap the entire tube fixture to the underside of the mesh. Please, it doesn't matter at this point whether you're moving him into his new enclosure next month, next week, or in a day or two, he's gotten no adequate
UVB light at all up until this point and this can and does end very badly on a regular basis for dragon owners, even after they put them under a very strong T5 UVB tube immediately after finding out that the mesh has prevented any proper
UVb light from getting to their dragon....