Solvent protector on a carpet will probably make it stretch, unless its a dry warm day and you can open the doors windows to let it through.
The solvent wicks down onto the backing and stretches it. It will look like the beach, looks like the fitter didnt fit it properly.
Ask me how I know, wont do it again, the shop knew what I had done.
Use water based, just tell them to put heating on and open windows, it will dry in about 4 hrs and full protection in 36 hrs, and leave them with blue over shoes.
Just be professional about it, find out what time fitters are leaving and get round just after, or if they are the last job, be round first thing in the morning.
Murky