You should have a great time at the Tres Islas, I've been going there for years and plan to keep going until I can find a 4* hotel, 4 hours from the UK, on a clothing optional beach and which doesn't rip you off for single rooms. Any ideas anyone?
If you want sunloungers which cater for naturists either go south, beyond the textiles and you should find that the last set of loungers beyond the lifeguard station are clothing optional.
Alternatively go north, out the back gate of the hotel (by the spa) and the loungers on that beach are used by both naturists and textiles.
As for walking along the shore, either way works, but going south I would leave it until after the naturist loungers.
And in my view you don't GIVE offence, other people TAKE it. Their choice!! Did I hear a splash from the punch bowl?
Dave G