Not a good idea.

Without a reservation you are likely to be told your interrail pass is not valid and need to pay full fare (plus a possible fine). 

I am sure others will advise you on alternative routings - possibly via trains to Lille and then TGV to Lyon.

To advise further we would need to know when you plan to travel.

A quick check on the IR planner with the reservations not required filter applied shows many routings with 3 or 4 changes that take between 8 and 12 hours. Some via Switzerland.

Can go nearly ev 2 hrs-in fact up to Geneve ev hour-via local trains with also better views and be happy that you took otherwise very expensive swiss trains. Learn to use app fuller; can also set to ´trains without RES´.