I'd say a mechanical relay is the perfect solution!
Anyway, the only thing to worry about is heat, then? There is no other wear on the unit?
Mechanical relays tend to be very reliable. But they are mechanical devices... Corrosion can cause them to get "stuck on" (rare) or it can cause resistance in the contacts. "Exercising" the relay tends to "wipe" the contacts, and it might be a good idea to exercise (and test) your relays once a year or so. If there is enough voltage on the contacts, that can help to "break through" the corrosion too. (People sometimes have trouble with small-signals through high-power relays.)
Where I work, we have a product that has several small relays. We have a spec for contact resistance and if the resistance is slighly high, there is a utility in our test program to exercise the relays. That usually brings them into spec. Sometimes we get "stuck" relays during production & burn-in, but we rarely get a field-failure. If a unit is returned for repair, usually something else is wrong (not a failed relay). Sometimes the resistance is out-of-spec, but never enough to cause a problem for the customer. And I'd say most of the time, the exercise routine will bring it back into spec.