It was inevitable that we would need to look at the work of Richard Paul Roe at some time. After losing a game of 'who knows the most famous Icelanders' it has fallen to me.
Like Diana Price, Roe disingenuously decided to 'withhold' any personal preference for actual candidates in the authorship question, preferring to concentrate on the accuracy of the geography of the Italian plays. It does, however, neatly absolve him from the need to explain some big inconsistencies such as the presence of inland waterways which might plausibly allow Shakespeare's characters to sail between inland destinations which have totally implausible tides which they are hurrying to catch. Not only do canals not have tides, there are no tides anywhere in the Mediterranean area, something visitors tend to observe.
Roe decides not to engage in Oxfordian argument and limit his contribution to proving that Shakespeare went to Italy. There could, of course, be creditable motives for this. Tying actual places named in the plays to real Italian locations, could almost certainly (favourite Oxfordian phrase) prove (another) that the author had visited Italy.
Possible location of the wrong tree, up which Oxfordians like to bark
There are, however, three problems inherent in his argument, especially if it is intended to support De Vere (and since destinations not included in De Vere's trip of 1574/5 do not appear to feature, assumptions beg to be assumed).