Easements are referenced in your deed, there is often a document at the registry of deeds to which you will have to refer. However, in addition to this, if you have a condo, you are now also going to need to look at the condo docs to find the specific restrictions.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
The prior answer from the Mass lawyer was off-base. Your deed won't reference easements.
If you closed your purchase through a title company, look through your closing papers you received to see if you received copies of the encumbrances on your title, which will include such easements. If you didn't get compies of those documents, your title company will probably provide copies for free. You can also look them up in the Bexar county property records at the county clerk's office. Once you get copies - READ the document to see what it says. If it's typical utility easements, it probably says nothing permanent, and nothing that would obstruct the visual observation of the right of way/easement from the air. Basically, none of your suggestions "pass the test" and are subejct to being torn down if the utility wants them removed (and they will probably send you the bill for doing so).
You mention your HOA - if your neighborhood's deed restrictions also have restrictions, you/your property is also subject to them, too. Again - get a copy (they are also filed of record and you can get them from your title company, and probably from the HOA, too) - READ them. You are bound by them. Perhaps you could request and be granted a variance from a deed restriction by the HOA, but the HOA can't speak for a utility company. In addition to the HOA being able to enforce deed restrictions, the city can enforce them, too. You can be subject to fines from both, and potentially other penalties from the city.