This is an awful, terrible idea. You might as well just get rid of Penning at that point. Tackle and Guard play vastly different. It's like moving a RB to WR, or WR to RB. Just because both are ball handlers doesn't mean they can do it.
Your trying to start Pennings career all over again. He goes back to be a rookie and very well may not succeed there so you essentially replaced a position that had a good player when you have holes in quite literally every other position on the team.
This is a move I would expect the Al Davis Raiders or the Cleveland Browns to make. Or even the 0-16 Detroit Lions. There is just simply nothing logical about it.
There is also no reason to suspect Campbell will succeed as Guard.
Just hand your 1st pick away to another team that will actually make use of it so your not ruining the careers of players.