You, presumably, have 2 vital dates............ferry into EU, and ferry out of EU.
The rest is up to you, don't have any plans, be ultra flexible, go where your heart takes you, see below for our last trip, based on the "rules" above:-
Froggie Spain / Portugal trip 7/4/2017 to 25/7/2017
Total distance, door to door................1670Miles
Total distance in Spain / Portugal .....1230Miles
Max altitude reached 1107m, 3632ft (Portugese/Spanish border)
Fuel burned (UK Gallons) .................61.3 Gallons
MPG for trip.......................................27.24Mpg
Oil used.............................................0
Other fluids incl coolant used............0
Total nights away...............................18
Nights on ship(s) ...............................2
Night stops:-
1 Cap Finistere Ferry
2 Cabarceno Aire
3 Colunga Campsite
4 Cadavedo Campsite
5 Foz Aire
6 A Coruna (Pillars of Hercules) Aire
7 Leis Campsite
8 Leis Campsite
9 Finisterre Aire
10 Arcade Aire
11 Amarante Campsite
12 Vila Real Campsite
13 Braganca Aire
14 Braganca Aire
15 Leon Aire
16 Burgos Aire
17 Cabarceno Aire
18 Pont Aven Ferry
Nights on Ferries..................2
Nights on Aires ....................10
Nights on Campsites...........6
Pics taken............................400
Wine brought back...............19 (Incl Port)
Total Cost (Incl Ferries and door to door here) £1986 (£52.26 per day per person)
Enjoy, and don't worry!!