Invisalign and Wire Retainer with Fake Tooth?

Here are few other options you have-
1. A wire and acrylic retainer (Hawley retainer/flipper)with the fake tooth attached to it. Cheapest option. But you do have to take it in and out.
2. A temporary lab processed composite Maryland Bridge. It is temporary fake tooth which has the fake wooth with two wings which attach to the back side of the adjacent teeth to the space. There is no cutting or shaping of adjacent teeth. THis is fixed and most esthetic option you have. But there is cost involved with this. I use this ruitinely for my patients. Good part is that Implant speciatist who will place the implant can shave the back side of the fake tooth and place the implant and you will eventually get a permanent tooth once you are ready. It is worth the cost for sure!!!

Your fear is justifiable as it is a front tooth. Your best option would be a sticky bridge (maryland bridge ) on adjacent tooth without any reduction. It will just move with the other teeth and no need to take it out until treatment is over.