You won't regret it, rats are the best pets
Some people use wooden enclosures with mesh fronts, so it could work, but that will depend on how large the vivarium is and whether the air flow within it is sufficient.
However, the surfaces may get very stinky (urine/scent marks will soak into untreated wood, and accumulate on/under the mesh, especially in each of the mesh corners. Plus, it's going to be difficult to attach all the necessary enrichment to the inside walls and ceiling.
Personally, I much prefer a cage. Pricewise, the best size for cost is currently the coco 100 (67.50 when using the discount code FANCYRATS here
https://www.littlepetwarehouse.co.uk/pr ... x54cm.html), but you can often find bargain bigger cages second hand.