Cardio on 4 day split

Anyone else on a 4 day split for F1 and do extra cardio as well?  Which days do you put it on?

So far I'm doing both rock climbing and swimming.
I'm attempting to make rock climbing as much "skill work" as possible. Go in, hit some crimpy holds and followup with some pinches/slopers and get outta there. I'm trying not to do too many juggy or pumpy climbs.
Swimming I do as cardio, I get 0 cardio and I know I need to start doing it. I have bad knees, so it's mainly one of the few cardio options I have.
I'm attemping to do something like
Monday - F7 in the morning, climbing at night
Tuesday - Swimming in morning, mobility at night
Wednesday - Rest
Thursday - F7 in the morning, climbing at night.
Friday - Swimming in morning, mobility at night
Saturday - I usually flip flop around depending on how I feel. Always mobility, but it's a toss up between climbing and F7.

I feel like I'm making good progress with f7 only 2-3 times a week.

I run 6-7x a week, each day averaging 7-9 miles or so. I do F1 work Monday, Tuesday, Thursday, and Friday, and play around on rings Saturday and sometimes after my Monday and Thursday sessions. I think you can put it in anywhere really, but I would have 1-2 TRUE rest days a week. I feel fine doing my program though, but then again I've built up to it.

I started to do 1or 2 Intervall Sprint Sessions on my rest days (something 8x50-100m, ramping up gradually) + mobility work and that works for me quite well. When i start my next cycle next week i plan on adding 1 or 2 days with some light steady state cardio as well amd see how it goes.