It’s an interesting idea, and good multi-use repurposing. Â If you use Tyvek (i’m assuming Homewrap? 1443R “kite” tyvek would not be good), make sure you reinforce the pole pockets well. Homewrap isn’t particularly strong for it’s weight and it’s abrasion and puncture resistance is moderate, rather than excellent (compared to something like 40D silnylon which is a similar weight). Â Also, keep it out of the sun, because many forms of Tyvek are very susceptible to UV damage.
One reservation i have, is that using a non air permeable fabric (like Tyvek, silnylon, cuben, etc) for the back will tend to feel uncomfortable, especially on a warmer day. Breathable/air porous fabric would be definitely more comfortable in those conditions.