I'm probably a bit late but I just found this thread and hoped my experience might help.

I toured Ireland on a Pacer in April 2010, using a Tubus Vega (Fly with platform) and Ortlieb back roller plus panniers. I am 6'4", 210lbs with EU size 46 feet, using a 60cm frame and had no problem with heel strike. I do ride to work with panniers every single day (Lemond Fillmore with fly rack) though so perhaps my technique will have helped with this. I also used an Ortlieb bar bag.

I carried light but complete camping kit (sleeping bag, stoves, tent, thermarest etc.) as well as cycling gear, wet weather and general stuff. I also fitted in a spare Conti 4 Season in case the terrible Irish roads got the better of me! But the combination of my strong Exal rims and the 4 seasons was bombproof. The Vega was a fair choice as it can take a reasonable balanced load but offers more flexibility than the Fly as you can bungee a tent neatly on top, between the panniers.

I used rubberised p-clamps on the seat stays as suggested above (Tubus do a kit which also includes the aluminium spacers to set the rack further back if you wish - I did not do this), and while there was a bit of movement/wobble I covered around 800km and only had to tighten the bolts once. Impossible to say how much stress I put through the braze-ons as there are no visible signs of weakening, but I'm still riding it and I'll keep going as long as it does! It's a good point though.

I think the Pacer is a great choice for light touring and would recommend it to anyone. By no means do I think it necessary to tow a trailer. If a rear rack does not provide enough space or you feel cannot take enough weight I would consider swapping out the fork for one with braze-ons for a front rack. This would allow the heaviest items to be carried forward. I have almost done this myself a couple of times but have resisted the urge to tinker any further!

Good luck with whatever you decide.