I agree with just about everything Rick has already said, but I'd like to add my preferences and re-state some of what he said.
- First of all, I like operating with a portable identifier. Maybe it's that I'm old school, and "grew up" when they were required. But I think it's helpful to let folks know that you are not in your home district.
- Yes, I realize the call is shorter when you start with a four-character call and not a six-character call. But I've operated a lot with a three-character "suffix" (both /KH2 and /KH6), so it was just as long (and neither was required by the rules.) I have also operated portable from the lower 48 (/1, /2, /3, /4, /6, /8, and /0), and each time operated with the identifier. And as Rick said, once you set it up in your macros, it's painless.
- But most of my portable operating was from specific, fixed sites: clubs in CO and CA, rental houses in MA, FL and MI, my parents' house in NJ, a park in PA, and a hotel parking lot in CO. Only a few times did I operate from "a spot alongside the road", and that was two short operations (a few hours each) from DE. (I called them "DExpeditions".) If I had been operating like KC3FL and N7WE did, multiple stops per day over a period of many days, I would probably do what they did and operate /M and/or /P.
- I remember a series of discussions on the (old) reflector before Rick went on the road, about how eQSL and LoTW operate, and the ways they each can be manipulated for portable operations. Here are what I consider the key points:
-- For LoTW, you need a separate certificate for each callsign, but your certificate does NOT show your actual station location other than DXCC entity. You can define the station location within TQSL, and you can define multiple station locations within TQSL and select the correct one for each log upload. I had separate certificates for all the portable identifiers listed above, and most had only one location associated with them. But /3 and /0 had multiple locations that I could select when I uploaded.
-- As Rick said, a certificate is associated with a single DXCC entity. Since I used W3HF/KH2 and W3HF/KH6 on the air, I needed a different certificate (from W3HF) for each for both reasons--different callsign and different DXCC entity. Be careful if you use the same call from different DXCC--you can get different certificates, but you need to be very careful about selecting the right one when you upload. Somewhere there's an operator who used the same callsign (legally) from both South Shetlands and Antarctica, but the QSL manager uploaded both logs with a single certificate and overwrote a bunch of confirmations.
-- For eQSL, you don't need certificates (of course), but you have to create separate accounts for each callsign. (These can be linked for awards purposes.) If you re-use a call from different locations, you need to set up separate accounts or sub-accounts that define the time periods when you were operating from different locations.
- I think the solution Rick came up with is a good approach for anyone who will operate for short durations at each site. Most of my operations were long durations--multiple days, sometimes spread over multiple years--so I chose something different.