I've been up and down the beaches last January (2009) from Indian Shores, then Passe-a-Grille and then by the USCG Blackthorne Memorial (by the north
Skyway fishing pier) , but at the time I didn't have a good dx'ing radio and so I just parked and used my car radio for dx
'ing and I didn't have very much time and/or patience to eek out all the stations you did.
As I got further south than Indian Shores, WWL 870 started booming in (the was early afternoon) as I got further south and there was less interference from WGUL 860, but I was not able to get 740 out of Houston, the Orlando station seemed to rule 740 at all three locations where I stopped. I did get 1060 out of New Orleans and some Panhandle stations.
In February of this year, late morning to early afternoon, I had to go to Sarasota (and regret that I left my Grundig at home) and what I did notice that surprised me was that 620 WDAE was suffering from Cuban interference in the middle of the day once I got to the beaches. (Ana Maria, Holmes Beach, Bradenton Beach, Longboat Key etc)........ WDAE was still dominant, but the Cuban station was plainly audible underneath it. At the time 620 out of Cuba was Radio Reloj, now they have changed their format on 600, 610, and 620 from Radio Reloj to a music and talk format).
Also I totally forgot to check 1600 to see if I could get the station out of Key West, since even on the SKyway the splatter from WRXB 1590 made that impossible. (I have received the Key West station on 1600 before on US 41/Tamiami Trail in the Laurel and Casey Key area)
Will have to try again, most likely when the weather cools down.
drt,
st. pete